In the background code, how does one set and obtain the attributes of subcontrols in a user control?

>>> 1. How do I set and obtain the attributes of subcontrols in the user control in the background code?

Add public properties/methods in your codebehind class for your usercontrol and declare in your page class:

Protected yourusercontrolcodebehindclass yourusercontrolid;

..

If you don't have a codebehind class, you can always do

Usercontrol c = (usercontrol) findcontrol ("yourusercontrolid ");

Textbox TB = (textbox) C. findcontrol ("yourtextboxidinyourusercontrol );
TB. Text = "123 ";

>>> 2. How do I set and obtain the attributes of the user control in the background?

If you have a codebehind class for your usercontrol, you can do
Protected yourusercontrolcodebehindclass yourusercontrolid;

Youruser controlid. property1 = "123 ";

Otherwise, you have to use reflection