thing's you'll need:
MATERIALS
1 door (20$) make sure it is solid wood, its more expensive but definitely worth it
1 2x4 for supports (5$)
1 strip of molding. (3$)
POWERTOOLS
(dont feel bad asking an adult for help!! I did!)
Jigsaw
Drill
Sander
OTHERTHINGS
wood glue
L- brackets (0.99$)
Screws/bolts (0.99$)
Paint (6$)

The door I bought was not symetrical, and it drove me crazy so my method was to first make the door look even and then worry about measurements. (not the best way, but it gave me the look I wanted). The picture shows the original door and the cuts I made.

First you wanna lever apart the top of the door so that the top molding slips right out.
Then make the cuts(using the jigsaw) to make it so when you slide the top molding back on, the two panels on the door are level. The dotted line is where you make the cut and the solid line is where the top panel ends up.
Last trim the thicker bottom to match the thinner top.

Cutting tips: cut along the back side of your headboard, it creates smoother cuts on the front.

Yay woodglue

put everything back together!
cut the molding to match the top of the headboard and sand to your hearts desire.

Paint Paint Paint!
(dont use spraypaint. It was a fail)

next attatch the 2x4's to the back of the headboard using the l brackets.

you can then attatch the 2x4 to your bedframe using the bolts or you could let it rest on the ground (which is what I am doing)

Yay Done.
:)