I have been wanting to make a chalkboard that I can easily update with the seasons/holidays. (I took down that huge ridiculous one on the odd ledge). This one was really easy to make and it turned out perfect. I used an old 23" picture frame with it's "artwork" still intact that I had bought last spring at a thrift store for $3 that I didn't end up using for what I originally bought it for.
Here is the frame and insert BEFORE:
I used Rustoleum's Chalkboard Paint and a small roller set and just painted it right onto the poster. This worked because the poster was already adhered to a cardboard backing, otherwise it would have been too thin. In that case I would have had to cut wood to fit the frame or bought a frame with a wood backing that I could paint. The paint went on great, just make sure you stir it really, really well first. It will look like it has a blue tint but don't worry.
For the frame I just used a standard white flat spray paint. It was indoor/outdoor Premium Decor paint in white and I actually really liked it - it went on really well and even and the nozzle was nice and wide so my finger didnt get sore (!)
The chalkboard paint said it should dry for 3 days so I let it sit in the garage for 3 days just to be safe! Then I got my chalk and seasoned the chalkboard before writing on it. This means I turned the chalk on its' side and rubbed it on the entire chalkboard then wiped it off. It is important to do this with any chalkboard so that this initial seasoning will fill any holes/ porous spots so that when you write on it the first time it doesn't stay like a ghost print in the background forever.