How the draft system works and who was drafted (age, socioeconomic status, “class” (upper, middle, lower) etc…). then, tell me the ways many americans expressed their disagreement with the draft, either with symbolic gestures or taking actions to literally avoid being drafted.

The draft system used to work a bit differently than it does now but the key principles are that youth affects the draft since those in their 20s almost always get drafted. As soon as a person turns 18 they have to sign up for the draft and usually older people don't participate in the war. 

When it comes to the socioeconomic status, the draft usually was focused on those from poor backgrounds or from the working class. Upper class members would rarely get drafted for war unless they wanted to get drafted personally. For example, if you're at a university there is a lower chance of getting drafted than if you only had finished high-school.

Americans did many things to avoid getting drafted. Some even participated in public protesting and hid from the police that would take them to get drafted, going as far as to hiding in a different country. Others wanted to make it a symbolic thing and would burn their draft books publicly as a sign of protest. The people who avoided getting drafted were known as draft dodgers.