It is okay to drive as long as the CEL isn't flashing. CEL flashing means SHUT YOUR CAR OFF NOW, TOW TO DEALER. Regular CEL says "hey, uh, somethings not right, probably wont kill you".
Go to a parts store, they will let you scan the codes for free. Once you have the trouble codes, you can diagnose the problems from there. It could be something as simple as the gas cap not being on tight enough. Pull the codes!
I can also pull codes with my phone, but your profile doesn't say where you is located :|