Im 16 weight 180 I have two 25 pound dummbells what workout do I do an how many sets idont want to lose weight only gain

Sets of what, there are dozens of exercises to do with them,

And you build up to more and more, till the weight is nothing and then you go up in weight

Umm this is my area of expertise and I'm even stumped.
We can't really give you a workout plan without knowing what your goal is.

Are you trying to bulk your arms?
Throw hits harder?
Are you trying to achieve a good looking body by working multiple areas?

You said you only want to gain but didn't go into further detail about what that meant.