Things you'll need:
 Blue Painters tape
 A knife
 Glass jar
 Armour Etch Cream
 Alphabet stickers
1. Use the stickers to spell out whatever word you wish to etch. With the painters tape create a border. Press all edges down thoroughly.
2. Spread the etching cream over the letters. It's almost the consistency of frosting, and who doesn't love more frosting so put it on thick. (Watch for air bubbles that may form, pop them or the etching will be splotchy.)
3. After 5 minutes, scrape the excess etching cream off with the knife. It is re-usable, save the extra creme by putting it back into the bottle.
4. Wash the remaining cream off in the sink with water. At this point, the glass will look like nothing happen. That's just fine- move on to the next step.
5. The fun part, peal the tape and stickers off to reveal the new & improved glass jar.
A few tips: If the glass jar is recycled and has at one time had a label. The easiest way to get the label glue off is to soak it in a vinegar/ water solution overnight. Soaking the lid as well will get rid of any lingering smells.