I have a Reject button that when clicked, an alert message comes up asking the customer to fill in a certain box.  They click ok on the alert and the edit page comes up.  I'd like it to render to the field they are supposed to fill out, which is towards the bottom of the page.  

Here's whats going on in my code.  This is only for the customer users.  They click the Reject button, they get an alert message, they click ok.  The edit screen shows up and they can either add their reject comments and click Save or click Cancel.

Button code where customer logic happens:

//If current users profile is Customer Portal, fill in the current users name for Contact Rejected and fill in the current date and time 
if(profileName.indexOf("Customer")!=-1)
{
alert("You have selected to reject this change.  Please fill in the Contact Rejected Comments in the Rejected Information section towards the bottom this Change record.")
window.parent.location='/apex/rejectCustomer?Id={!Change__c.Id}&retURL=/{!Change__c.Id}';

 Apex Page:

<apex:page standardController="Change__c" extensions="rejectChangeCustomer" action="{!autorun}">


</apex:page>

 Apex Class:

public class rejectChangeCustomer
{
private final Change__c chge;    
public rejectChangeCustomer(ApexPages.StandardController controller) 
{        
this.chge=(Change__c)Controller.getrecord();     
}         
public pageReference autorun()
{          
ID Id =  ApexPages.CurrentPage().getParameters().get('Id');              

  
 
  

 PageReference retPage = new PageReference('/' + Id + '/e?retURL='+Id+'&00Na000000BA4IU=1&00Na000000BA4IW='+UserInfo.getName()+'&00Na000000BA4Ip=Rejected&00Na000000BA4IV='+DateTime.now().format().escapeHtml4()+'&saveURL='+Id);  
 retPage.setRedirect(true);
 return retPage;        
 }}