Hey Joe!
Soon we can welcome you to the club then! Exciting!
In regards to the Denon, since you are moving from traditional 2-channel to full fledged surround, I would strongly suggest you read the manual first (naturally) and excecute the Audyssey calibration procedure with patience and care to get the best out of it. If you have not already done so I'd urge you to get acquainted with Audyssey in general to find out more about it. Although automated, it is somewhat of a powerful calibration tool and reading up on it may prove beneficial.
http://www.audyssey.com/audio-technology/multeq
http://www.audyssey.com/audio-technology/multeq/tour
http://www.audyssey.com/audio-technology/multeq/how-to
https://audyssey.zendesk.com/home
1) use a steady tripod for the measuring microphone
2) make the room as quiet as possible and with no obstructions for the speakers (leave the room yourself, if possible)
3) place the mic according to the instructions by Audyssey/Denon
4) always utilize all 8 measuringpoints
Those are the basics. The whole idea is for Audyssey to gather as much information about your speakers and the acoustics of your room as possible. The more care you put into the set-up and speaker positioning the better results you'll get. Remember to experiment - every room is unique. But if you follow the basics and possibly re-calibrate a few times you'll understand better how the EQ-system works. Also laborate with the various Audyssey-settings once the calibration is complete ('flat'-setting sounds best in my room, for example). Keep in mind that settings done automatically sometimes need to be tweaked to your liking. Trust your ears. Worth remembering is also to re-calibrate when changing something in the room down the road. This is because things added or substracted to the room can have an effect on acoustics and may yield different EQ-results.
Let us know any other questions that might pop up! Enjoy the brilliance that is Apex!