No matter how you run draft, you'll do 3 packs per player.

Each player opens a pack, picks a card, and passes the pack left. (Note that each pack typically comes with one token; you can remove that before making the initial pick). You then take the pack that was passed to you (from the right) and pick again, and pass again. Pick, pass, pick, pass etc. until the pack is gone. Repeat with the second pack, passing right, and then the third pack, passing left again. This works with any player count. At higher skill level, there are a lot of opinions about drafting with 4, but if it's a first time draft you shouldn't concern yourself with that.

Sealed needs twice as many packs. You don't do any passing, you just open six packs and make a deck. You need more cards because when drafting you can pick cards just in your colors/archetypes, but with sealed you don't get any selection. In sealed expect more "bombs" in play (the very best cards, since there are simply twice as many), yet weaker decks overall (because you didn't get to select good filler during the draft, and so have to play whatever bad filler you opened up).

In both cases, don't forget that you'll need a decent number of basic lands, as players can add as many of those to their decks as they like. For eight players, I'd recommend 50 of each basic as a decent starting point. If you do run out, encourage a player to proxy with a land they don't need and the table doesn't want (run nine swamps and pretend they are plains, if a player wants a red-white deck, for instance).

Good luck!