How to gain mussel(arms)?

i would like to gain more mussel around my arms and i would like to stick to running for my legs i want to be in shape(or better shape) for when the pool opens(about 2 months) what are ways i can build arm mussel and i dont want to buy dumbells all i have(that i could find) are 2 3LB waights what can i do and how long do i have to do it in terms of hours and how many days each week