This is actually not really easy you know.
Okay, I'll give a quick explanation how the referral system works.
1. Refer your link to someone else
2. They register under you
3. They are considered your referral only when they pay the price after the trial
** If they did not pay after the 30-day trial, they are not qualified
4. As stated, get your $30
So the point here is that you need to find a person willing to spend money to their service before you get your profit. Good luck on that.
Its like a coinbase , if your referral purchased some bitcoins whatever requirements to qualify for referral commission, then only referral and the referrer will get the profit. If you referred 100 and no one spends anything , no profit at all. It means a total waste of time referring them.