The service engine light indicates many things. The main culprit is the gas cap not clicked 3 times when you put it back in after filling with gas. Remove the cap, put it back on and turn it till it clicks 3 times. After driving it for a few miles, the light may go off, otherwise, you will need to take it into Saturn or a GM mechanic to have the light reset.
If that;s not it, then you need to have the engine codes read. You can either goto a auto parts store and buy a code reader which runs typically from $50 up to hundreds. They come with a book which helps to decipher the codes. if you aren't technically inclined best to simply git-er-done and take you SC into the shop to let them take care of it.
FYI, the manual tranny is "filled for life" and should not under normal operating conditions be changed for 100K miles or slightly more. If you have just gotten the car, it is wise preventive measures to change all fluids anyways. The radiator fluid (if orange) is rated at 100K mi also. The spark plugs are rated at 30K mi. though. I highly reccomend having the plugs changed to platinim plugs, this will extend the life to 100K miles and give you better performance.