First thing you have to do with mussels is soak them in some cold water. Throw away any mussels that are already open. These are dead and should not be eaten. You want your mussels to still be alive. Eating a dead mussel can make you very sick.
Soaking the mussels in water should also let some of the gritty sand to be extruded out of the shellfish.
In a large pot, heat 2 tbsp. of butter with 2 cloves of the butter. As the butter begins to brown, add your chicken broth to the pot. As that begins to boil, now add your mussels. Cut your lemon in half, squeeze the juice over the mussels, and throw your lemon wedges into the pot. Put your lid over the mussels and let them steam. The mussels should be done in about 10-15 minutes.
While this is cooking, melt the rest of your butter and mix it with the garlic powder. Spread it over your bread. Take your remaining cloves of garlic, chop them and spread them over your bread pieces. Heat the bread in the oven for about 5 minutes. I like my garlic bread to still be pliable and soft, I just want it warm enough to have a slight crunch.
Once your mussels are cooked, sit down and enjoy this glorious meal!