Transmission problem

I have a 99 silverado 1500 5.3 motor, I
have never had any sort of problem wit
trany slipping or leaking but the
transmission line blew off back of radiator
and I replaced line and refilled wit fuilds
and no it won't go into 3rd and if o skip 3rd
to overdrive, the rpms are running high, I
don't feel like its the trany its self but Mayb
air in line, can it b that and how do I bleed
the line???