Go to the official MySpace website and click on the "MySpace Music" link. This will lead you to the page where you can sign your band or yourself up for a music account.
Input your email address and choose a password. You will be asked questions about your band name and the country and state you live in. MySpace will also ask you to confirm that you agree to their terms of service, which include not uploading or distributing music you do not own the copyrights to.
Prepare your music for upload to MySpace. Make sure the files are converted to MP3 format. From your profile page, upload the MP3 file to your page, inputting information on the song like title, album title and even the song lyrics if you want your listeners to be able to access them. Be sure to save your progress after you upload the files to your player.
Set up features on your account that will allow users to rate your music, and even download samples that could prompt them to pay to download the rest of your album. Your player will be visible on your MySpace profile.
Put the word out there so the MySpace community knows that you have music available to sample. Consider leaving posts to your profile in the music community forums and spread the word outside of MySpace as well. If you have a website, be sure to link your fans to the music player on your MySpace page.