<apex:page  controller="conTaskNew">
<apex:form >
       <apex:pageBlock id="mypageblock" title="Task Edit" mode="new">  
            <apex:pageBlockButtons >                    
            <apex:commandButton onclick="return lsave()"   action="{!save}" value="Save"/>
            </apex:pageBlockButtons>
            <apex:pageBlockSection title="Task Information" columns="2" id="theSection"> 
            <apex:inputField id="vDisposition" value="{!task.Disposition__c}"/> 
            <apex:inputField id="vActDate" value="{!task.ActivityDate}"/> 
     </apex:pageBlockSection>               
</apex:pageBlock>
</apex:form>
</apex:page>

public class conTaskNew {
   private Task taskobj;
        private String vleadid;
        private String vOwner;
        private String vemail;
        private String vwholead; 
        private String vwhatid;
        private String vdisposition;
        private String vactionbynewten;
        private Date vactivitydate;
        private String vsubject;
        private String vdesc;
        private String vstatus;
        String vid;
       
        
     public   conTaskNew(){  
               this.vleadid = ApexPages.currentPage().getParameters().get('lid');  
               this.vOwner= ApexPages.currentPage().getParameters().get('assignedTo'); 
     }
        
        
       public String getOwner(){
            return this.vOwner;
            }          
        
            
        public void setOwner(String pown){
            this.vOwner = pown;
            }
        
             public Task getTask() {                     
                     return taskobj;
                }
 
                public void setTask(Task taskdet) {
                      taskobj = taskdet;
                }
                                
        
       
        public String getWhoId(){
            return this.vwholead;
            }          
        
            
        public void setWhoId(String pwholead){
            this.vwholead = pwholead;
            }            

        public String getWhatId(){
            return this.vwhatid;
            }          
        
            
        public void setWhatId(String pwhatid){
            this.vwhatid = pwhatid;
            } 
        public String getDisposition(){
            return this.vdisposition;
            }          
        
            
        public void setDisposition(String pdisposition){
            this.vdisposition = pdisposition;
            }             
            

         public Date getActivityDate(){
            return this.vactivitydate;
            }          
        
            
        public void setActivityDate(Date pactivitydate){
            this.vactivitydate = pactivitydate;
            }  
            
       
        public PageReference save() {    
         
              
                
                 Lead leadrec=[Select ownerid from Lead where Id=:this.vleadid];     
                 this.vOwner = leadrec.Ownerid;   
                 Task newtask= new Task(
                 Subject=this.vsubject,  
                 WhoId= this.vleadid,
                 Ownerid= this.vOwner,                 
                 disposition__c= this.vdisposition,                 
                 activityDate= this.vactivitydate              
                 
                 );
                  try{
                      insert newtask;                     
                  }catch(Exception e){
                   throw e;
                  }
                     PageReference secondPage = new PageReference('/'+vleadid);
                     secondPage.setRedirect(true);
                     return secondPage;             
                 
       } 
}