if you are about to invest your time or maybe some resources for profit, then it is the right place to start.
If you bring players to this lottery you will get 90% of income generated by them, in the same manner as the owner - based on player wins. So 90% goes for you, 10% stays at the owner.
there are two functions for players to use, Play and PlayReferred. If some player will provide your address into PlayReferred function along with his numbers, then 90% of the fee (fee is equal to 1/100 of players withdrawal) will be assigned to referral_ledger mapping under your address. You can withdraw all the funds assigned to it at any point of time using Withdraw_referral() function.
A good way would be making an web interface which adds your address and passes it to PlayReferred function, posting it on your website and let people acces that website with Mist.
The good news is that there are other ways for that, you do not need to be deeply involved in any ethereum related stuff, or even know any programming language, lets say that you run a blog or youtube channel and you can convince people to play. Instruct them how to configure EthereumWallet (to watch contract), and ask them to provide your address in the PlayReferred() "Ref" field. Any referred player withdraw will then generate profit for you.
the 90% referrer fee may change in the future, but it is guaranteed (hardcoded in the contract) to be always at 50% or more