You can buy cryptocurrency use 10$..and also you can sel that crypto whet it gone up.it very eazy for you. You can use neteller, skrill, visa card,master card et to buy it. You can see it this link
I use it in for a long time(iq option started).This company link with iqoption company. You don't care about company just care about you crypto. You can buy bitcoin,litcoin,ethereum etc.
Other wise they don't have referral program. But you can earn some money buy and sell or invest crypto