How To Best Use SoundCloud?

I've got some cover tunes that I've created from scratch via MIDI, and I want to use SoundCloud to advertise my skill set to prospective clients.  Can someone pls advise the most effective way to do that?  OK, I know how to post a song, but do I need to be concerned with any legal issues since these aren't ORIGINAL tunes.  Also, I'm NOT selling the tune on SoundCloud, I'm just using it as a demo.
 
Tanx in Advance,
KC