The first thing to do, is drill a hole in the side, using a 3/4" (I think) holesaw. I really didn't pay attention, but know the correct size when I see it. (I'll verify this size when I can think to)
The hardware needed was purchased from Lowes, and this first item is located in the electrical dept., along with the other conduit fittings. The cost is around five bucks, and it is a watertight connection.
The second item is in the plumbing dept., and was less than five bucks.
Photo below - The electrical fitting, out of it's package. The locknut will not be needed, and someday i'll find a use for them in the garden.....Heh.
Photo below - The threads of the hose bibb were wrapped with teflon tape, which helps seal the threads, and also has some lubricating qualities about it - which makes it SO much easier to screw into the electrical hub. (Since the hub is made from aluminum, the threads want to gall - when screwed into another type of metal fitting).
Photo below - The 2 pieces screwed together. The locknut was removed, and is ready to attach to the barrel. See those aluminum threads on the electrical hub? They are really sharp, and make their own threads when screwed into the plastic barrel. Also, notice the black rubber seal that comes with it. This is what makes it a watertight connection.
Photo below - As you can see, the hole in the barrel is a tad smaller than the fitting, and it is simply screwed in by hand. Be careful not to continue screwing it into the barrel when all the threads are thru, because you could strip out the hole. Man, that would suck!
There. The spigot is installed, and the barrel can now be filled with rainwater.
This barrel ain't got much to say now, does it? Ha! This barrel was located about 20 feet away from the main raised bed, and a hose can easily be attached to the spigot, which will make watering that particular bed quite easy.
So, there ya have it......EG's rain barrel construction. Man....I have around 165-170 gallons of rainwater storage now! Yay me!
Take care, and happy gardening!