to change APN go to Options> Advanced Options > TCP -----> there you can enter APN; username; and password
Don't think there is any other resource to plug in the other information.....maybe all you need is that info and the rest gets defaulted.
The MMS settings should come from your provider when you download the Service Books for the BlackBerrry - - go to the carrier's BIS site and log in......and "Send Service Books"