I need help with trying to do split screen with audio (I have two videos of people talking)

I have two videos on two girls talking in their rooms. I am trying to create that effect where the videos are side by side, one video plays first & then the other videos plays with sound. I want it to look like two people are having a conversation. I have seen many videos on youtube on how to create the split screen effect however, I can not find one that includes any audio. I have tried to do what the videos say to do however, the audio does not move above the first clip (to stack them on top of each other). 

Please HELP ASAP! 

Thank you!