I used spray foam adhesive to secure the foam to the wood first so I didn't have I worry about it slipping around. I was also joining two pieces on each plank.
Leave the ends till last. You want a neat (as possible with all the bulk) fold. You need to play around with this to figure out how's best to do it, and staple to secure.
Sew it up and check again before hemming the top and bottom all around, and thread elastic through each hem. Slip it over your base again, and pull the elastic until you achieve the desired tension. Make sure it looks even all around and tie in a knot to secure. It should sit on top of the base under the mattress so you can't see the base at the corners where your mattress may not cover it, and you also shouldn't see any gathering as it will be hidden under the mattress and under the base. I left the tension a bit looser at the bottom so we could easily lift the band to access the drawers.
And if you missed it and would like to see more pretty picture of the finished headboard, click here, and if you have any questions, just ask in the comments below!
And no, I don't iron.