Sally, before you try anything else, get a rocket blower, such as this one:
http://www.warehouseexpress.com/prod...aspx?sku=13374
That will shift a lot of the dirt. If that's not enough, take your pick from a wide range of solutions available. Personally, I use digipads with Eclipse E2 fluid, available from warehouse express.
You might find reading this web site:
http://www.cleaningdigitalcameras.com/
highly informative.