There was a site that showed you how, but I forget it...

Well, Im going to give it a shot.

You'll need...
-One clear(not frosted), round lightbulb
-2 bendy straws(lol)
-The top of a 20oz soda bottle(cap and 1-2 inches of plastic)

1.Cut the end of the lightbulb off(part that screws into fictures)
2. Clear all the crap out of it
3. Run water through it to make sure all of the little peices of glass are out
4. Cut two holes on the top of the 20oz bottle cap(big enough for two straws)
5. Tape on the top of the 20oz bottle onto the top of the lightbulb(along with the cap)
6. Insert the two straws into the holes in the bottle cap

One straw is used to suck the vaporised weed through, the other so that air can enter the lightbulb while you're sucking through the other end

Unscrew the cap, put the weed into the lightbulb

Hold a lighter underneath the weed

Give it about 20 seconds

Breath in