The first part of this tutorial briefly shows you how to create an audio track and how to export (first 8 mins), while the later half will show you how to add intro and outro music. This is a YouTube video, so you can view it off campus OR you can view it here - you'll be asked to login to your Onedrive account.
**The video mentions a microphone - don't worry, you don't need a microphone. You can use your built in microphone for this.