Don't try if you are below 18, it is a bad habbit even if you are 18+. Like drugs, alcohol, sex abusing. Keep those away, are not good for our pockets, house, family, spouse and so on.
I think op is not asking for under age gambling. But that is fact gambling could turn into worse habit in case of addiction. I also think it is very dangerous for any person not even for newbie. The best is not to get start with gambling even with risk free offers too.