[Dmitry at Pelican Parts]

Hello and welcome to the forum! I was not able to find a DIY tutorial for the rear window, but am attaching the procedure for the front window which should help you as a general guide. I would also suggest doing a quick search throughout the forum to see if this has been covered somewhere. Best of luck!

BMW E90 Front Window Regulator Replacement | E91, E92, E93 | Pelican Parts DIY Maintenance Article