There are a multitude of ways to create green flames this is meerly one of them. I like this one because the chemicals required are really easy to get a hold of. First here's a video of it in action:

and at night . . .

The orange color you see near the middle is actually the match itself burning not the solution . . .if i hadn't dropped it in it would have been pure green.

Step 1: Gather Materials

This is actually incredibly easy to do . . . .you'll need:

Boric Acid: commonly sold as roach killer at stores like home depot this large bottle cost about $6 and has enough for several hundred fires
Methanol: WARNING!!!! this stuff is extraordinarily dangerous . . . .if you inhale its fumes, drink it, or absorb it through your skin it could kill you and if it doesn't do that you'll probably be blind. . . .use extreme caution!!! You can buy it under the guise of "Heet" or gas line antifreeze from Walmart or any other store selling car equipment and chemicals.

*a ceramic container to burn stuff in . . .needs to be something that can take a great deal of heat.
As you'll be dealing with an alchohol fire it's important to exercise appropriate caution . . .it's extremely flammable.

Step 2: Mix

Strap on a face shield and an apron and take your chemicals outside away from anything flammable.

Pour about a teaspoon of your boric acid into the bottom of your container.

Carefully unscrew the cap of the Heet and make sure not to breathe in the fumes. Pour a few teaspoons on top of the boric acid.

Stir carefully so you don't spill anything.

You're now ready for some entertaining fire!

Step 3: Light!

Light a match(I had a match stick left over from some matchstick rockets) and carefully drop it into the solution. If you've got long matches you can simply touch the burning match to the solution and retrieve it. This will ensure you don't get any yellows or oranges . . .I think those make it kinda interesting but that's just a matter of personal taste.

WARNING::: the fumes created by the mixture before you light it are also flammable. Do not under any circumstances attempt to light this simply with a bic or other cigarette lighter . . .

If you do this at night it's even cooler.

Sit back and enjoy some colorful fire!