Unless you've got alot of money, it's not going to happen if you do it legally. You need to get licences from each of the record companies you're going to sell tracks from and pay royalties each time a download is made. You'll need to pay for solicitors/lawyers too. Plus, they're not even going to look at you if you're just a hobbyist, you'll need an accountant, a real registered company, etc etc.
Also you'd need a good CMS which can be costly depending on what you want to achieve. It's best to do this with small local bands in your home town or area. Those you can easily get permission for usually.