Button to Load Movie on main stage

Hi, I’m trying to load a movie using a button. I’m sure this has been discussed in earlier threads, but I’m new to AS3 having a really hard time finding the correct solution for my needs. I just want the button, when hit, to load an external .swf file inside the movie clip playing.

In AS1, (I never did learn AS2) this is what the button command said
on (release) {
loadMovieNum(”About.swf”, 0);
}
So how would this translate into AS3?

Please help…I feel like I’m going in circles. Thanks in advance