There 2 kinds of disability.Social security disability insurance which is disability base off of how much work you have done.For some one under the age of 24 I think you would need at least 1 years and 5 mouths of work time.
Then there is Supplemental Security Income which is made for people that don't meet the work requirement for Social security disability insurance.Thats what me and gloomy have.
Either way you have to start by going down to your social security office to fill out the paper work.There very strict on the requirements to get disability.You have to have lot of paper work from your doctor and your therapist proving your disability and even then they will sometime send you to there own doctor or therapist.
After that it's a waiting game some times it can be months or even years before they make a decision.I have no idea why some people get it faster then other.For me it took 2 years to get it but I have heard of people getting it faster then that.On the plus side you get all the money from when you first turn in the paper work.Which is called a retrocheck.As far as how much money you get if you qualify for it.It depends on what state you are in.Some states the federal government handle all the money and in other states some of it come from the federal government and the rest is supplemented be the state.
Good luck on anyone that want disability it's not fun trying to get it.