All the screws here are not clarified of their lengths

You can use double sided tape, foam or regular scotch,3m to reattach it.

The steps do not tell you what length screw that is needed to be here. What I can tell you that is the screw needs to be 5mm or 6mm, NOT 7.5 or 8mm or 9mm.

Cita de BeatJunkie:

To confirm what HandyMac and colmcostelloe found, some MacBooks have one 3mm and two 4mm screws in the rear wall of the battery compartment. On the one I worked on, the shorter 3mm screw came from the middle hole.

Thanks Beat Junkie, this was the situation with my Mac 2.13ghz Mid 2009 that I was putting back together. Thanks for the confirmation! (For the 6th step)

On the 2.13ghz MacBooks, there is a 3mm screw holding down the Magsafe connector, when putting it back together make sure this is secured after connecting the magsafe connector to the board, otherwise you'll have a wobbly Magsafe connector.