create form

[C# Programming]

Hi
How can i use a function in classes when that function exist in codebehind of a form ?

and :

I use -private void checkBox1_CheckedChanged(object sender, EventArgs e)- in codebehind;
Now i want to use checkBox1_CheckedChanged in another event again;
but compiler doesn't allow me and compiler error me that argument is necessary.
What should i do?