Start by drilling a hole near the bottom of the barrel. This is where your spigot will go, so be sure to use a drill bit that's a little smaller than or the same size as the spigot.
Place a metal washer onto the threaded end of spigot, then put a snugly fitting rubber washer over the threads to help hold the washer in place and prevent leakage.
Apply a bead of waterproof sealant over your rubber washer and then insert the spigot into the hole. Once the sealant has dried, run a rubber washer, followed by a metal washer onto the threads of the spigot inside the barrel. To hold the spigot snugly in place, secure it with a hose clamp. This will ensure you spigot doesn’t come loose from the barrel.
So the water can enter the rain barrel from your home’s downspout... carefully cut a whole in the lid. For your exit, drill a couple of holes near the top of your trash can to accommodate water overflow.
Create a barrier to pesky mosquitoes and leaves by cutting a piece of landscaping fabric and placing it over the top of your barrel. Then put your carefully cut lid on the barrel.
With the construction of your barrel complete, simply place it under your home’s downspout. Now all you have to do is wait for it to rain.