Brook, welcome to TFP!! :-D Without knowing which pump you have, it's very (!) hard to help you. There is a sticky in the "Pool School" section http://www.troublefreepool.com/viewtopic.php?t=52 which tries to explain the need for specific info about your pool when asking questions (the person who wrote it is awesome!!! ) Without knowing you pump, you can try to loosen the lid with the pump running - this often works. Other pumps have 'torque points' which can have a 2X4 or wrench applied to them so as to facilitate lid removal.
If you'd post back with the pump type, someone here is almost sure to have a similar model and can give you specific help 8)
Again, welcome to this forum!! we will do our best to help answer any future questions you may have!