Replace wheel bearing assembly 2002 grand prix gt

Took car in for wheel alignment. Was told front wheel bearings getting bad and recommend replacement. How tough is this to do myself? I’ve replaced rotors and brakes but never bearings. Saw Utube video and it doesn’t look that bad. Any suggestions? And does the assembly come in “one piece” pregreased or do I need to grease bearings myself?

If you’re thinking about it just get a repair manual. It will pay for itself several times over.