Gather a replacement toilet seat, screwdriver, and possibly adjustable pliers
Lift the old seat and locate the hinge bolts at the back of the toilet
Remove the bolt caps if present
Hold the nut underneath the bowl if needed
Unscrew the bolts from the top or bottom
Remove the old seat and hinges
Clean the mounting area on the toilet bowl
Align the new seat hinges with the bolt holes
Insert the new bolts and tighten the nuts
Make sure the seat is centered and secure
Tighten until snug without over-tightening
Test the seat and lid for proper movement