Place a plastic retainer washer (if included), a metal washer, and then a nut onto each of the closet bolts. Tighten the nuts by hand first. Then, use your wrench to snug them down, alternating between the left and right sides. Tighten each nut a half-turn at a time to ensure even pressure is applied to the base. The toilet should feel stable and not wobble. Be extremely careful not to overtighten, as this will crack the porcelain. Stop tightening as soon as the toilet is secure.