Tried to access the photos at the link you provided to see how the velcro might be designed to attach the fly to the poles and/or inner tent, but could only get an "under heavy load" message. Must be a lot of folks looking at your tent.
From what you said in your first post for this thread, I gather that your tent poles do not go through sleeves on the inner tent as shown in photos of an earlier version of the Evolution that you included with that first posting, but instead the poles for your tent apparently attach some other way to the inner tent (clip, maybe).
As you can see in those photos of the earlier Evolution in your first post, a black strip of velcro is sewn onto the sleeves about half way down from the peak to each of the four corners. The underside of the fly for that version of the Evolution has pairs of velcro strips about three or four inches long that mate with the velcro that's sewn into the sleeves, which secures the fly to the poles and to the inner tent itself via the sleeves. I know this because that's the version I have.
Don't know that my experience with a sleeved version would aid you in figuring out how to use the velcro on the fly to secure the fly to your Evolution's poles and/or inner tent, but here's a problem I ran into -- and how it was resolved --
I took the following photos of my Evolution (2007 version) when I first pitched it upon delivery back in 2007 to show that the velcro strips on the underside of the fly DID NOT align with the velcro sewn onto the pole sleeves halfway from the peak to each of the four corners --
Since the four sets of velcro strips on the underside of the fly did not align at any of the four attachment points on the pole sleeves, the fly could not be secured to the inner tent and poles at all without greatly distorting the fly, poles, and innertent -- which I didn't attempt since I didn't want to damage something.
The problem was fixed by Big Sky having the tent and fly returned for correction of the misaligned velcro as I described in a posting at the following thread --
Moral: If you can't figure out how the velco on the fly should be used to attach the fly to the poles or inner tent, maybe it actually needs "fixing" by Big Sky. Or maybe not. Best idea is send Big Sky an email asking for guidance.
Hope that helps.
Oh, and the tent has performed great! Here it is in the Winds last year:
and on the Teton Crest Trail two years earlier:
Not a "paid" promo, and -- just like the fish in the photo below --- not a fish story either!!! (excuse the drift, just couldn't resist ;>) --