Writing to file from C# .NET

Question

hello friends I am new to .net. I have created a form in C# with various check buttons and text buttons for user options. I cannot collect all this data and write to a file.
 
I was able to put code that wrote to a file in the program.cs file. But now how do I write code to collect the text box data and checkbutton option (which are in the form.cs files)?
 
So I wanna know how to access the checkbutton options and text buttons from program.cs.
 
Is there another way to do this? i.e collect user data from texbox and checkbuttons and put to a file?
 
Please help.
 
Thakns 
 
Please gimme some hint.