Yes, Yes, Yes. That is one of our unique features. You are renting storage space on our server. You can put anything on it for sale that you want with the exception of unauthorized cover songs.
The other download sites require that a song is commercially released on CD before it can be sold. CD sales are in major decline. It doesn't make sense to have to spend the money to produce and manufacture a CD which is going to sit around unsold when you can sell the music directly.