I think you are alright so far. Pull the back tight side to side and put a few staples in that seam. Make sure it is on tacking strip so it will be covered by wire-on. Don't staple any further then this area for now. Next go to the front. Raise front header up 6" or so, center material and put a few staples in each outer edge pull it snug but not too tight. Now carefully lower header making sure you don't pull out your staples or tear your material. Header should hang loose about an inch or so above windshield if not adjust front. I usually put a piece of foam or something between header and windshield for support. Now go to the back quarters and work the top forward and down on each side area at the rear bow. The area around rear quarter windows is one of the last things you do but you might need to clamp them in place while adjusting to get wrinkles out. Now you have to remove the bottom tack rail in and out about 50 more times to make adj. intil it's perfect or you get sick of it and call it good enough which ever comes first
Hope this helps.