I'll write about how to spread your music on the Internet later. But, first, here's what you need to do ONCE YOU HAVE DECENT MATERIAL to share (nice demos, studio-quality songs): create profiles for you/your band on the following sites:
Myspace-
Soundcloud-
Reverbnation -
Bandcamp -
The Sixtyone
Make sure you are able to manage all of them. You should keep them updated, preferrably with new songs every three weeks or so. Keep people interested in what you're up to.
Your profiles MUST have:
1. Songs (duh). Make sure people are able to download at least 2 songs. Don't be afraid to give your stuff for free. People won't buy what they don't know. Give them a chance to fall in love with your music and make them WANT to have your full album or EP.
2. Photos / Videos
3. Short biography and release
4. Link to your official website (if you have one -> you should)
5. Link to your twitter account (highly recommended)
6. Influences
7. Who you sound like. Don't be cocky. Don't write "I sound like myself". We all have influences and we all sound a bit like one singer/band. This is actually a good thing, trust me. Try to use indie bands as a referral. Don't say you sound like Nick Drake . OK, you can mention him, but try to include singers like Ray LaMontagne or Bon Iver, for instance. This will give your new listeners/potencial fans a chance to fall in love with a singer who's similar to another singer they just met. In other words: they'll be THRILLED to discover SO MANY GREAT ARTISTS, one after the other.
NOW GET TO WORK!