Step 1: Find a frame with the glass intact. I just went to my basement and found one that we were no longer using. Cost--FREE.
Step 2: Remove Glass from the frame. Keep all the other "stuff" from the back of the glass.
Step 3: Take sandpaper and scratch the glass all up. I went in both directions. It is just giving the blackboard paint something to adhere too. I used sandpaper we already had in the garage.
Step 4: Wash the glass.
Step 5: In a well-ventalated room or outside, set glass on a piece of cardboard or across a tub or something. You don't want to the glass to get dirt or grass on it.
Step 6: Shake your "Chalkboard" Spray Paint. I used Rustoleum's Chalkboard Paint. I got it at JoAnn's Fabrics and Craft store and I had a 50% off coupon--Thus $3.85 after my coupon was deducted.
Step 7: In quick, even strokes, spray the scratched up side of the glass. You don't want to linger too long on one spot. You will give it lots of coats to ensure a nice, even finish.
Step 8: Let dry for about an hour
Step 9: Spray second coat.
Step 10: Follow steps 8 and 9 until you are happy with your chalkboard.
Step 11: Once completely dry, put glass back in frame, chalkboard side out. Put all of the "stuff" you removed, back into the frame.
Step 12: Hang your chalkboard!
All done! :)