When u click on New Button (Account Page) its goes to A VF Page where 3 fiels like Account Name ,Account Number ,Account Phone No
 and one Save Button...............................
<apex:page standardController="Account">
  
     <apex:form >  
     <apex:pageBlock >    
     <apex:pageBlockButtons >
       <apex:commandButton value="Save" action="{!save}"/>
  <apex:commandButton action="{!cancel}" value="Cancel"/>
     </apex:pageBlockButtons>
   
   <apex:pageBlockSection title="Enter Account Details">        
          <apex:inputField value="{!Account.Name}"/>            
          <apex:inputField value="{!Account.accountNumber}"/> 
          <apex:inputField value="{!account.Phone}"/>
    </apex:pageBlockSection>
    </apex:pageBlock>
    </apex:form>
</apex:page>.........
 When u click on Save Button (VF Page) ​​it will goes to another new VF page Where Account Name Auto Populated With a ("Go To Contact") Button .......................
<apex:page standardController="Account" extensions="Contact">
<apex:form >
 <apex:pageBlock >
 <apex:pageBlockButtons >
 <apex:commandButton value="GoToContact" action="{!Contact1}"/>
 </apex:pageBlockButtons>
    <apex:pageBlockSection title="Account Details">
         <apex:outputField value="{!Account.Name}"/>
         <apex:outputField value="{!Account.accountNumber}"/> 
          <apex:outputField value="{!account.Phone}"/>
     </apex:pageBlockSection>
   </apex:pageBlock>
   </apex:form>
  </apex:page>

and class code is ..

public with sharing class Contact {
   public Account a{get; set;}
    public Contact(ApexPages.StandardController controller) {
       }
      string id =  Apexpages.currentpage().getParameters().get('id');
    public pagereference contact1()
    {
    PageReference requestPage = new pagereference('https://ap2.salesforce.com/003/o'+a);
        return page.contactpage.setredirect(true);
    }
 }

 When u click on "​Go To Contact" Button it will goes to contact detail page(custome vf page) where  Account Name ,Account Number ,Account Phone No will populated in new contact ..

Hear i am facing problem ....

<apex:page standardController="Contact" extensions="Contact">
  <apex:form >  
     <apex:pageBlock >    
     <apex:pageBlockButtons >
       <apex:commandButton value="Save" action="{!save}"/>
       
   </apex:pageBlockButtons>
       <apex:pageBlockSection title="Enter Contact Details">   
          <apex:inputField value="{!Contact.id}"/>   
            
         <apex:outputField value="{!contact.Account.Name}"/>
          <apex:inputField value="{!Contact.Name}"/>         
          <apex:inputField value="{!Contact.Phone}"/>   
        </apex:pageBlockSection>
      </apex:pageBlock>
    </apex:form>
  </apex:page>

n class code 
public with sharing class Contact {
   public Account a{get; set;}
    public Contact(ApexPages.StandardController controller) {
   
         
      }
      string id =  Apexpages.currentpage().getParameters().get('id');
    public pagereference contact1()
    {
    PageReference requestPage = new pagereference('https://ap2.salesforce.com/003/o'+a);
        return page.contactpage.setredirect(true);
    }
 }