Problem with a counter

Hi this is the problem i am having!

I have a movie that loads questions for the user to answer, the frist screen has a start button, when the user hits the start button a movie is loaded at random into content, a timer then starts.

What i want is when the user hits the start button for a counter to keep track of the questions, when the user has answered 11 questions i want the thing to terminate.

What action script could i use to do this. I have a textbox called with a variable name counter on the stage, and the start button has an instance name start_btn.

Any help would be appreciated!