Drain the olives and put them in a food processor.  Add the garlic, anchovy fillets (including the oil), a squeeze of lemon juice and black pepper to taste.  Process while slowly adding the olive oil so that you get a smooth paste that's not too runny.  You can add more olives if you like but don't leave out the anchovies.  That's what gives the tapenade it's character.  No salt needed, as both the olives and anchovies are salty.  Serve with water crackers or sliced toasted baguettes.