Jam over a backing track in a band's lens, then drop in your take — the shop tells you how that player would've changed it. The backing is generated (no recordings); your solo is your own audio.
1 · pick a backing
2 · whose style are you going for?
3 · drop in your solo (record over the backing, then upload)
live in-browser recording is the next step; for now record on your phone/DAW and upload.