Greetings! i'm stuck trying to add the captcha to my visualforce page for web2lead... i'm not an expert with the code so i'll really appreciate some help.

I'm using this class for the captcha

001 public class reCAPTCHA {
002 
003     /* Configuration */
004 
005     // The API endpoint for the reCAPTCHA service
006     private static String baseUrl = 'https://www.google.com/recaptcha/api/verify';
007 
008     // The keys you get by signing up for reCAPTCHA for your domain
009     private static String privateKey = 'your_private_key';
010     public String publicKey {
011         get { return 'your_public_key'; }
012     }
013 
014     /* Implementation */
015     
016     // Simple form fields for the example form
017     public String myName { get; set; }
018     public String myEmail { get; set; }
019     
020     // Create properties for the non-VF component input fields generated
021     // by the reCAPTCHA JavaScript.
022     public String challenge {
023         get {
024             return ApexPages.currentPage().getParameters().get('recaptcha_challenge_field');
025         }
026     }
027     public String response  {
028         get {
029             return ApexPages.currentPage().getParameters().get('recaptcha_response_field');
030         }
031     }
032     
033     // Whether the submission has passed reCAPTCHA validation or not
034     public Boolean verified { get; private set; }
035     
036     public reCAPTCHA() {
037         this.verified = false;
038     }
039     
040     public PageReference verify() {
041         System.debug('reCAPTCHA verification attempt');
042         // On first page load, form is empty, so no request to make yet
043         if ( challenge == null || response == null ) {
044             System.debug('reCAPTCHA verification attempt with empty form');
045             return null;
046         }
047                     
048         HttpResponse r = makeRequest(baseUrl,
049             'privatekey=' + privateKey +
050             '&remoteip='  + remoteHost +
051             '&challenge=' + challenge +
052             '&response='  + response
053         );
054         
055         if ( r!= null ) {
056             this.verified = (r.getBody().startsWithIgnoreCase('true'));
057         }
058         
059         if(this.verified) {
060             // If they pass verification, you might do something interesting here
061             // Or simply return a PageReference to the "next" page
062             return null;
063         }
064         else {
065             // stay on page to re-try reCAPTCHA
066             return null;
067         }
068     }
069 
070     public PageReference reset() {
071         return null;
072     } 
073 
074     /* Private helper methods */
075     
076     private static HttpResponse makeRequest(string url, string body)  {
077         HttpResponse response = null;
078         HttpRequest req = new HttpRequest(); 
079         req.setEndpoint(url);
080         req.setMethod('POST');
081         req.setBody (body);
082         try {
083             Http http = new Http();
084             response = http.send(req);
085             System.debug('reCAPTCHA response: ' + response);
086             System.debug('reCAPTCHA body: ' + response.getBody());
087         } catch(System.Exception e) {
088             System.debug('ERROR: ' + e);
089         }
090         return response;
091     } 
092         
093     private String remoteHost {
094         get {
095             String ret = '127.0.0.1';
096             // also could use x-original-remote-host
097             Map<String, String> hdrs = ApexPages.currentPage().getHeaders();
098             if (hdrs.get('x-original-remote-addr')!= null)
099                 ret =  hdrs.get('x-original-remote-addr');
100             else if (hdrs.get('X-Salesforce-SIP')!= null)
101                 ret =  hdrs.get('X-Salesforce-SIP');
102             return ret;
103         }
104     }
105 }

And here is my web2lead vf page

<apex:page standardController="Lead" extensions="myWeb2LeadExtension" title="Interesado en Contratar Servicios de MCM" showHeader="false" standardStylesheets="true">    

  <apex:composition template="{!$Site.Template}">    

<apex:define name="body">  

    <apex:form >

      <apex:messages id="error" styleClass="errorMsg" layout="table" style="margin-top:1em; background-color: #FF9300" />     

    <apex:pageBlock title="" mode="edit" id="sider2_header">    

       <apex:pageBlockButtons >  

           <apex:commandButton value="Enviar" action="{!saveLead}" />        

   </apex:pageBlockButtons>     

      <apex:pageBlockSection title="Solicitud de Información" collapsible="true" columns="3" >              

       <apex:inputField value="{!Lead.FirstName}" label="Nombre (s)" required="True" style="width: 300px; height: auto; background-color:  #E0FFFF" styleclass="input"/>         

   <apex:inputField value="{!Lead.LastName}" label="Apellido (s)" required="True" style="width: 300px; height: auto; background-color:  #E0FFFF" styleclass="input"/>           

<apex:inputField value="{!Lead.Email}" required="True" style="width: 300px; height: auto; background-color:  #E0FFFF" styleclass="input"/>   

<apex:inputField value="{!Lead.Phone}" required="True" style="width: 300px; height: auto; background-color:  #E0FFFF" styleclass="input"/>

 <apex:inputField value="{!Lead.Company}" required="True" style="width: 300px; height: auto; background-color:  #E0FFFF" styleclass="input"/>

 <apex:inputField value="{!Lead.NumberOfEmployees}" Label="Número Aproximado de Empleados" style="width: 300px; height: auto; background-color:  #E0FFFF" styleclass="input"/>           

<apex:inputField value="{!Lead.Industry}" style="width: 300px; height: auto; background-color:  #E0FFFF" styleclass="input" />           

<apex:inputField value="{!Lead.Street}" style="width: 300px; height: auto; background-color:  #E0FFFF" styleclass="input"/>           

<apex:inputField value="{!Lead.City}" style="width: 300px; height: auto; background-color:  #E0FFFF" styleclass="input"/>           

<apex:inputField value="{!Lead.State}" style="width: 300px; height: auto; background-color:  #E0FFFF" styleclass="input"/>           

<apex:inputField value="{!Lead.PostalCode}" style="width: 300px; height: aut; background-color:  #E0FFFF" styleclass="input"/>   

 <apex:inputField value="{!Lead.ProductoInteres__c}" style="width: Auto; height: auto; background-color:  #E0FFFF" styleclass="input"/>

 <apex:inputField value="{!Lead.ProveedoresVozActual__c}" label="Proveedor Actual de Voz" style="width: Auto; height: auto;background-color:  #E0FFFF" styleclass="input"/>           

<apex:inputField value="{!Lead.ProveedoresDatosActual__c}" label="Proveedor Actual de Datos" style="width: Auto; height: auto;background-color:  #E0FFFF" styleclass="input" />

<apex:inputField value="{!Lead.Description}" Label="Comentarios" style="width: 300px; height: 600; background-color:  #E0FFFF" styleclass="input"/> </apex:pageBlockSection>

       </apex:pageBlock>     

</apex:form>    

</apex:define>  

  </apex:composition>

  </apex:page>

So i don't know where i need to star!!!

What i would like to do is, when load the page, hide the send button, add the captcha to the form... if the captcha is correct, then show the Send button and send the information to  salesforce, if the captcha is not valid then send a message to try again but without reload the page...

Again, thank you so much... and i'll really appreciate your help!!!