I use sound click and sound cloud as well as BOX for my tunes..... depends on the mood I'm in when I get ready to upload it.
Yes..... once you get the whole how to upload thing worked out..... post the song link in the songs forum and state exactly what you're looking for in the form of feed back....
If it's for listening pleasure say so, if you want mix crits, try to detail what you think might be going on or what you're looking to accomplish. People will come back with good advice for you in most cases.