Debug User Control

Debug User Control:

• Open the Default.aspx page that is part of your EP Web Application project. This is an ASP.NET page that can host web parts needed for testing User Controls. The Default.aspx page is automatically included in any EP Web Application project you create.
• Configure the web parts on the Default.aspx page.
• Add any EP Proxy Projects that are required for your EP Web Application project.
• Run the Default.aspx page.
  
  http://msdn.microsoft.com/EN-US/library/cc616458.aspx 

How to debug user controls
http://msdn.microsoft.com/EN-US/library/cc567649.aspx

Create EP Web App,
Add an User Control
Add ManagedContentItem to Default.aspx
Add EP Proxy Project (VS->Project->add AOT Proxy Project)
Run Default.aspx

 ManagedConentItem in general is the usercontrol name.

How to modify an user control
http://ajstudi0.blogspot.com/2013/02/walkthrough-adding-field-to-user.html