This is about the most simple headboard you could make.
Step 1: Sand & Stain the Wood
I purchased 7 pieces of 6' long boards (tongue and groove boards that are 7" wide).
Here is what it looks like after I stained a few of the boards a driftwood color.
Step 2: Screw Them Together
Next fit the pieces as close together as you want them and take two 6' 1"x4" boards and screw all the boards to the top half of those boards. I came up a little short on top so I added just a little length to the top.
Step 3: Enjoy Your New Headboard
Carry that headboard into the bedroom and rest it against the wall. Then scoot the bed up to the headboard and enjoy!
Bonus points for draping some cute little saying over the top.