Cropping out someone's face from picture and overlaying just the face into a video

Question

Hi.
I posted a couple times here about using AE to do the following for a video. Though I changed up the idea a little. Here it goes:
Imagine this video. A youth hockey game and the kids are lined up on the bench and the announcer calls their names and one by one they skate out from the game and onto the ice.
During this intro, I have added their names in scrolling text as they come out onto the ice. I used windows live movie maker and saved it as a video.
Then I put that video into After Effects so that I could then put a pic of each kid's face next to their name. I used the team photo and cropped out each player's face to use for this. I used the GIMP program to do the cropping.
However, I cropped them out in a rectangular shape. So when their name scrolls across the video at the bottom of the screen, their face then shows up beside their name but in rectangular form. In the background of the kid's face is whatever was there in the team photo. So basically it's their teammate's or coach's pants or jersey.
To make this all look better, I want JUST the kid's head and shoulders as the image beside their name. Not a rectangular pic with stuff in the background. So the shape of the image is essentially just their head and shoulders. The shape of the pic in any picture program will always be rectangular but what I want is a transparent background so that when I overlay the kid's face onto the video beside their name, all we see is their head and shoulders.
With GIMP, I can use the select tool and trace around their head and shoulders and "crop to image" and hopefully that makes the background transparent. But what I need to know is if I can then overlay it onto the video in AE and get the result that I'm looking for.
Can someone tell me if they have any experience with this? Overlaying any image onto a video in AE is easy, but doing it the way I want to is not clear to me.
Thanks for the responses.

Answer 1

You can either use masks in AE to cut the kids out or, if you save out of Gimp in a format that supports alpha, you can just import the already cut-out picture. Also, as I mentioned in a previous thread to you, if you have the heads cut out and saved in a format that supports alpha, you could drop the heads in with Premiere too.
You really need to start here: Getting started with After Effects After Effects is many leagues more complicated than something like Windows Movie Maker. You will land in even more frustrations if you skip a foundation.