Peel off the first couple scraggly outer layers of the corn husk, leaving the majority of the layers for protection (don't remove all the layers).
Turn on your grill to medium heat (about 350 degrees). Gently pull the husks of the corn back -- but do not completely remove them. The goal is to get the corn husks as far back as possible in order to remove the silk. This is a messy process, so make sure to do it over the sink or a trash can.
If desired, you can brush the corn kernels with olive oil or butter at this time (as some people suggest), but I prefer to add the butter once it's all cooked and ready to eat. Personal preference.
Carefully reposition the husks back over the corn, layering from the inside and then outward to cover as much of the interior corn as possible. If you'd like, go ahead and tie each ear with a piece of loose husk. I don't and it works fine for me.
Place the ears of corn on the grill over direct heat. Rotate as needed to keep it from getting too cooked or even burned on one side. After a couple of turns (about 3-5 minutes), place the ears of corn over indirect heat (to the side of the grill) and close the cover. Keep the cover closed for 15-20 minutes over indirect heat, turning every 5 or so minutes.
You'll know the corn is ready to remove from the grill when the husk begins to darken and pull away from the tip of the ear and the kernels are tender when pierced with a knife.
Carefully remove the corn from the grill using tongs or oven mitts.
Peel the charred corn husks from the corn (over the sink) to expose the cooked corn. Some ashes will get on the corn and this is ok. If you really want them removed, just run under warm water for a quick minute.