First of all... you might want to try searching as there is a TON of information about how to install a valve/spigot in many types and shapes of pots.
Things to watch out for...
food-grade metal, so Brass or Stainless valve.
Silicone is not going to give you a long lasting seal
Cutting a hole is the hardest part
Just do a quick search for adding a valve to a pot here and you'll get all the info you could ever want!
MrShake - Top Hat Brewery and Tapworks
Owner of BrewTroller