Welcome !!!!
"Like how to install the legs properly..."
Set the lid & grates aside, turn bowl upside down, gently twist out the legs, line up the handle (either one) with the front leg, having the the back legs then set in first (gentle twisting, do not rock back & forth) find the small hole on the front leg & hook that little bent knuckle looking thing on the front of the wheel triangle into the hole ( the very end of it should end up pointing DOWN )
.....then gently twist in the front leg......all this sounds much more complex than it really is......
Oh, and WELCOME !!!!