I need some help. I need to "snap-on" the passenger side mirror. The housing is still intact, but not sure how to snap a new mirror into place

Thoughts?

My dad had knocked mine off with a mail box a couple years back. I think, if i remember right, you have to pull the casing off... it's triangular, it just pops off, then you have to unscrew a few screws... and unplug the electrical wires from each other (assuming yours is electric) plug the new one in, then screw it in, and pop the triangular casing back on. It's actually pretty simple. So, if I missed a step, you'll probably catch on quickly.

Hope it helps