Go to Noble's site, I'm sure it explains everything there.
For most bonuses you need to play a certain # of raked hands in order to get the bonus money. Lets says its 5x the hands of the amount your bonus is:
You deposit $100, you would get a $100 bonus so you would have to play 500 raked hands in order to get the $100 bonus. Most sites give you a percentage of the bonus when you complete a percentage of the hands.
So in the example above, you might complete 100 raked hands and you would recieve $20 in bonus (20% of the bonus requiremnet= 20% of the bonus)
Just go to Noble and read...