Whats wrong with my bronco 2?

i have a 89 bronco 2 5 speed. i drove it 1 day from work and it wouldnt go n gear so i pulled over an checked the resvoir under the hood. it was empty so i filled it up and its smoothed out a bit. now the truck will take off with me even when i have the clutch n. and once i put the truck n neutral the only way 2 get it n gear is 2 shut it off. i've heard it needs bled or my slave needs replaced and i need 2 no so ne help would b great. and if ne1 no's where the bleeder vlve is or the slave is on this truck. thanks