Well, I was going to write a tutorial on how I made these, but then I realized that I just combined a few other people's tutorials and they probably explained things much better than I could. So I figured I'd just link to their tutorials and give any tips and tricks I picked up while making them. (Also I made these over a year ago and just got the photos off my camera yesterday, so the details are a bit fuzzy. Whoops.)
Main Tutorial used: Cre8tive Design's How to make a tailored valance
I ended up mostly going the route of Cre8tive Design's tutorial, however I used a 1x2 board instead of the 1x4 she recommends. My valances were going in our sewing/sun room and one window is against the sliding glass door to go outside so I didn't want them sticking 4 inches out and getting in the way. The blinds themselves are also inset in the window frame so I didn't have to worry about the valances sticking out far enough to cover them.
I didn't cover the boards in white fabric before attaching my batik because I'm lazy and no one would be standing under them looking up at the unfinished wood. I'm all about saving time.
My fabric was also 14 in wide, so I just left it as is and hemmed the one end. I stapled the other end to the boards without hemming it since my valances were going to be right up against the ceiling and no one would see a raw edge.
As you can see here, I didn't have the fabric go all the way over the top of the board. I wanted as much length as possible and with only 14 in to work with, I had to get clever. And as I said, the boards were going very close to the ceiling so no one would see if the fabric didn't entirely cover the top.
Also, staple guns are awesome. What else can I make with these things?!?!
These L brackets were super easy to install. We ended up using 3 per window since they were pretty long and we didn't want the valances to bow in the middle.