if configured properly you should be able to dial from your address book. when you make a LD distance if you see the pop up "Connecting via MyGlobalTalk" then the app is working. Note that there is a glitch in the app in that it does not recognize countries where you have to dial a "1" first. To get around that you have to enable "Use for US Long Distance Calls" before making those types of calls. This way you don't have to reconfigure numbers in your address book.
Took me about 3 tries at CS before someone was able to give me the right answer.