How can I make a button available and usable in every file of a Visual Studio Project?

Question

Hello together,

I have a problem with my Visual Studio 2008 Project. I have 5 .cs-files in it. I need to be able to make all my elements available in every file.

Example: I want to use a button in a .cs-file (because there is the function I need the button to be in), but VS says, that there is no context to this element in this specific file. In another .cs-file of my project it's no problem.

It's probably quite easy to solve, but I have no idea how I can make this possible.

Thank you!