Do you have a BB data plan? Gotta have that first.
Some carriers hide/disable BBMaps and I thin ATT is one. Suggest you use our SEARCH feature and also look at the 9000 section. This was the first ATT device that had that "problem" I think.
Are you using the following link for Google Maps? Make sure the version you are downloading is for your specific device and OS. Google Maps for mobile
GPS would be under the Options menu. Not that familiar with OS 5 however.