It's quite easy. First you have to set up a Premium DS Logon account. To do so go to milConnect to register.
If I'm trying to access my uncle's records who was discharged in 1982, what conditions apply?
If you are not their next of kin, you may only be able to request limited information from their Military Personnel File.
I'm trying to access my uncle's record so that he can have a military burial, where do I call?