HOMCOM A90-196 Instructions D'assemblage page 8

Tighten nut onto screw with included wrench.
Repeat on other side
Place the nuts and washers to the side for
now.
Place the washers over the screws from
seat cushion.
Take nuts and washers off of the seat
cushion.
Fit seat post onto seat cushion screws.
Finger tighten each nut onto the screws
from seat cushion. If difficult to tighten, nut
may be upside-down.