Buying is one way to get it. Have the intention to buy every month for me a decision that I admire because you are still a dozen years of age.
You are trying to do something very beautiful for the future of finance.
I wish you success with the consistency you will do.

OP. My question is the same as LoyceV, have you considered the place to store the Bitcoin that you will buy every month with the amount of $100. If not, study it first because it is wrong in choosing a storage area, it can be fatal.