To roast the garlic, cut the tops off so that you can see the cloves peeking through the outer layers. Wrap in tinfoil, and bake at 350 for about an hour. When the garlic has cooled, squeeze the cloves out through the holes you created on the top, by starting with the bottom and working your way up. I like to mix mine in equal proportions with butter and mash it all together.
FWIW, I find that this works just as well with green as it does dried garlic.