This prob dumb question but how get to level 4, been playin awhile and don't seem to advance

same way you got there to rank 3
keep shooting down enemies and bombing hangars, carriers, winning missions etc...
the higher the rank, the harder it gets that's why you can get better planes too!

Thank you for your time. I think its partly I stink and I could use some wifi. Most awesome game thanks for that also. Was really startin to wonder why. Finally did come up and won't give up. Totally addicted!