Honda Repair: Headlight warning and bad gas mileage, gas mileage, dome light

Question
I have two problems with my 95 Civic (2 door).  Firstly, the indicator "ding" for when you leave your headlights on is not working.  My dome light, keys in ignition warning, dashlights etc. are working.  Is this some simple repair?

Also, I'm getting about 17 mpg.  I just had a tune up and fluids checked/changed.  Any obvious thing I should look for that might be causing this problem?

I just bought this car used so don't have any history on it although the seller claimed it got great gas mileage.

Thank you!

Answer
Sandra:
The warning ding should be a plug in component under the dash. It should be fairly easy to replace, once you have the new one you will see what you are looking for, it is probably by the other warning indicators. At $2+ a gallon 17 MPG is not good, there are several things to check, I would take it back to who did the tune up and tell them to check things over because your mileage is so bad. Does it ping when you go up hills? It could be the timing. Does is have plenty of power? Give the mechanic as many facts as you can so the can properly diagnosis or it could be something they did.
Good luck.
Bill