What tools?
If you want to promote yourself/ music on the internet then you should understand the power and influence of social media. You can build your social network influence and share music through ping.fm
What methods?
Social network/ media marketing, e-mail marketing, and if you have budget you can offer promo's, special offers, and giveaways.
What should you promote?
Your music and your content (e.g guides, how to's, etc.)
How do you grow your web presence?
Create relationships. Answer inquiries, questions, and feedbacks. This is the only way to keep yourself in touch with your audience.