Blackberry 7290 help

I recently bought a Blackberry 7290. I am new to this and I am having some trouble. I can never keep a signal for the phone. I may get one for a few minutes but if i try to use it, it cuts out. Am I doing someting wrong. I think that it is strange that I can't get any service with it. Any help would be appreciated.

You might try sharing some additional information such as where you are located and what carrier you are using.