How do I get music for linerider?

This depends if you want music in the actual game, or if you want to make a video with music in it and your good track. Fortunaetly, now you can do both.

To put in in your video, you have to put the line rider clip you captured onto the timeline, and at the same time, put some music in the the audio section.

To put it in your track, you can now upload songs, since they now made it with silverlight.

Hope this helps :-)