Go to Autozone. Buy the 98 Accord "Haynes Manual". Read the page on how to check a CEL. It is VERY simple, all you need is a paperclip or some sort of wire. Under the dash there is a place where you connect the wire or paperclip into two holes, then a light flashes in a secquence on your dash. You interpret the sequence of flashes based on what is written in the Haynes manual.

It is important to know why the CEL activated. Knowing this will give you an understanding of what is wrong with your car and hopefully you can convey this information to the dealership. This can hopefully prevent the dealer from screwing you, which they ultimately may try to do. Go from there...