National Guard Security Clearance.?

Im going to need a security clearance for 11B in the natinoal guard. How do they conduct a security clearance? Do they just look into your criminal history? or other things? I've been totally truthfull about my criminal history and am getting a waiver for a mis marijuana charge. Im not really sure if i have anything from when i was a juvi, My recruiter got my criminal record from the courthouse and no juvi charges were on it. Isnt my juvi record sealed? I dont want some juvi charge i forgot about to come back n bite me in the ****.