Creating an Event Listener

I’m trying to learn how to create an event listener with ActionScript 2 in Flash CS6. I took over some Flash projects at work and know only basic code, and have nobody to help with the more complex stuff! I’ve looked at quite a few tutorials and forum posts but can’t figure out how to use the other code I’ve seen in my own project. I’ll try to describe as best as I can.

My main file has two movie clips called “content_mc” and “sideNav_mc” that I am loading and swapping swfs into. In the swf loaded into “content_mc” I have six buttons. When one of these buttons is clicked, it needs to load “menu.swf” into “sideNav_mc” and then gotoAndPlay the frame that correponds with the button that was clicked. So if a user clicks “button3_btn” then “menu.swf” will load and automatically start at frame 3.

Can anyone help me figure out what code to use for this, using the swf/instance names I provided above? Thanks!