How to get Commercial Use license?

[wishonmusic]

Hello everyone,
Could you please explain me the following;

1)What is a commercial use license? and what kind of a thing it is? (Image pdf or what?)

2. How do I give commercial rights for my creations?

3)Do I have to get my creations copyrighted from a third party? If so can you please suggest me some third parties to get licensed my works (Sheet music and beats)

Thanks in advance.