Can anyone help a newbie?

I’ve got programming experience, but i’m just getting into actionscript. My question is this: how can you make a stationary object rotate to “track” another object moving accross the screen? Basically, for one of my tests, I want to have an object doing a random motion (which i’ve already completed), and I want another stationary object with a pointer to be constantly pointing in the direction of the moving object. i know i have to play with rotation, but i really don’t know where to start. Can anyone help?

Thanks in advance!