The goal is to keep the AHI below 5 but since you're just starting, don't worry about that too much right now. Get used to the machine, get the right mask, then worry about tweaking the settings further to get below 5.
One thing to do, though, is to make sure the clock is right. ResMed machines reset themselves at noon, whatever "noon" is according to it's clock. Any data available on the screen is gone (but is on the card) after noon.
Another think to help is knowing the alphabet soup:
Apnea Board Moderator
Breathe deeply and count to zen.