Problem is, if you can't figure that out, should you really be using
dangerous power tools? Let Darwin decide I guess. Insert the round end of
the chuck key into the hole in the side of the chuck so the bevel gears
engage. Turn the key clockwise to tighten, anti-clockwise to loosen. There
are three little jaws in the chuck that protrude from the end of the chuck
as it tightens, clamping the drill. Insert the plain end of the drill bit
into the chuck. If you insert the pointy end you will have difficulty
drilling a hole.

What a condescending prat you are!