Getting your music into the most popular distribution channels (Amazon, iTunes etc) is really easy, but there are many different people offering this service for varying amounts of money but in my opinion there's only one way to do this correct.
The right way to get your work online.
I recommend Tunecore for getting your work into the right places because their reporting is brilliant, the interface easy to use and the promotional opportunities are great. I used Tunecore when I ran my own record label and the reporting made paying royalties a LOT easier!