Need Help! Z Axis, BK/BF12 mount.

Hi guys, i purchased a BK12 and BF12 with Ballscrew to use in my Z Axis.

Im trying to figure how mount it, when i roll the ballscrew the nut come very tight, the BF12 come with some spacers but or aim using it bad or dont works.

Can someone know some doc or video about how are the right way to mount it?

Thanks in advance