Ldylee,
Welcome aboard. I'll assume you already have a song (or a piece of a song) in wav or mp3 format. If not ask about that and I or someone else here will help you there.
If you have a wav file you'll need to convert that to an mp3 in order to upload it to a site. This is also done because wav files are pretty big and need to be compressed so they can be downloaded/streamed quickly. If you need an mp3 converter you can find Lame32 in the listings at this site:
www.hitsquad.com/smm
Now you have an mp3 and you're ready to go online and set your site up. There are lots of free sites out there for posting your music, the biggest probably MP3.com and IUMA.com. Alot of folks here use Nowhereradio.com. Nowhereradio is good because unlike MP3.com you don't have to wait a week for the song to be cleared. On Nowhereradio the song is available as soon as you upload it.
The 3 sites I mentioned above are all very easy to use. Just go there, open an artist account (they are all free) and fill out the information section. Lastly, you'll upload your material (which you can do on a dial up modem, although quicker on a broadband connection).
Once your done with that drop a link here and we can give you some feedback. I hope this helps you and let me know if you need further clarification.
Stray
