Use an onEnterFrame or a setInterval loop. IE:

onEnterFrame = function(){
//Put Code Here;
}

Or:

function myCode(){
//Put Code Here;
}

And also please note, that the onEnterFrame is an event that belongs to a
movieclip. And every movieclip can have just one onEnterFrame. In my code, the
code defines an onEnterFrame function for the current movieclip.

And then there's setInterval. You can have as many as you want, and they are
independent of the frame rate.

NOTE: the naming is a bit confusing for some people

onEnterFrame (or onClipEvent(enterFrame)) doesn't happen when you enter a
frame .. it happens at the frame rate, starting with the next display after
the handler is set.

the code inside a frame DOES happen only when you enter a frame (from
another frame).
--
All the best,
Jeckyl