The L2 commission % will allow you do reward affiliates for telling other people to become an affiliate. 
When someone signs up as an affiliate, they can promote your programs. When they do so and someone buys, because they are the direct affiliate, they will get a commission. If the affiliate also refers to other people to register and become an affiliate, he will become a parent affiliate, and they will also earn an L2 commission.
L2 Commission will only work if the Affliliate registration page (optin page) is added in your Affiliate links and will be shared by the parent affiliate. If someone signs up as affiliate using the affiliate link, the user will become a Level 2 affiliate.
For someone to be able to share a link and let them know about the affiliate system:
- On an Optin Page, go to Form settings > Register to affiliate program > Select Affiliate Program. An extra step here is needed, and that is to add the Optin page to the Affiliate Program.
To do this, we need to go to Affiliate Links.
You can setup a new link, make sure you enable it for the program you want to share with your friends.
When this link is used, people who register will become affiliates, but affiliate who shared the link will become the parent affiliate.
Whenever an affiliate is a “parent” affiliate, he is the parent for every commission program, even if they, themselves do not belong to that program.
If you go to Manage Affiliates, and edit one Affiliate Profile, you will be able to see and edit the Parent Affiliate for that person. 