Hash: resin from the hemp-plant ("cannabis sativa") pressed together in little cubes or slices, colour ranges from light brown to black.
With a lighter, gently heat the cubes/slices of hash till you are able to crumble it. Don't burn it. You could use a pair of pliers as well.
Weed (marihuana): dried flowering tops of the female hemp-plant, looks like dried flower-tops or (when cut:) tea-like, colour ranges from grey-green to brown-green.
If it's not cut already, do so with a pair of scissors.
How much?
This really is difficult. It depends on the strength of the material, the high you want to get and the number of people involved. If it's your first time, it's best to smoke with someone who has some experience. He or she could comfort you during your first trip as well. If you haven't got a clue of the dosage; smoke slowly, in a comfortable place with nice people, and stop when you feel you've had enough.
