Add soundtrack to video in After effects

I have the source code of our project (in After Effects) for a video animation of 2mn19 : [login to view URL] We need to change the soundtrack to French (we have it in mp3) we should put on, and a few English texts in the video to change in French (all will be sent: mp3 and txt). Also we need to extend a few scenes to stick to sound. Please, send us some of your creations.