MR.T

OK I have just started to learn how to program in python yesterday and I have never programed before that, that being said please don't flame me to much if this is a really stupid question.

OK heres what I want to do, I have a button made using tkinter and when I click that button it runs a function(I have all that set up already), now what I want the function to do is to add a number to a global variable and have that variable keep that value,for example if the variable originally equals 0 then when I click the button the variable would equal 1 and if I click the button a second time the variable would equal 2 and so on.

So how would I do that?

thanks in advance