Referencing user controls in ascx

Hello,
I have set up an ascx file with user controls.
Also added a line to the aspx file which will be using the ascx controls as below.
<%@ Register TagPrefix="EC" TagName="CommonEmp" Src="EmpCommon.ascx" %> I need to now access the controls in ascx file in the aspx.cs file. And I can't seem to figure out how to do it.
I tried several things, but they do not work.
using myNameSpace.EmpCommon;
Also tried
MyDB.EmpCommon smec = new MyDB.EmpCommon();
But they do not wok.
I need to populate the controls based on whether I am adding or updating the data. 
Any help would be greatly appreciated. Thanks in advance.