First off don't use sound recorder.

Get something like Acid Pro 4.0 or Cool Edit Pro 2 to record your shit with (I personally like Acid Pro cause it's easier to work with, but most peeps use Cool Edit for some reason).

To get your shit on the internet get an account at one of these places.

www.soundclick.com
www.coolgoose.com
www.dmusic.com

Sign up as a band or what not and just follow the instructions on how to upload your music. You'll probably have to put it in mp3 format.

Making your shit sound professional, it's mostly reliant upon the sound card you have in your computer. Cheaper sound cards that will give you pretty nice quality range from about $100-$300. After that it's mainly your production like voice over's adlibs, echo effects and shit like that, which both of the programs I mentioneed should have.

If you're near a fairly large college you can probably go in and ask if they have a studio... if they have one it will probably be free to use, although they might not be the greatest.