Hi, I am trying to do a three tier architecture of windows application using C#. Main layout: Inserting Values into a datagridview from two textboxes. Problem : I have 3 layers in my application UI,Business,Data Layers.(form1.cs,Bal.cs,Dal.cs) I have created separate c# code files for each, the question is how can I use the textbox or any other controls from form1.cs to dal.cs is there any way doing that. I am learning how to work with tiered architecture please provide me some help. Thank you.