But if you have a new laminate countertop, that's probably your next step. Your new sink will have instructions of some kind on cutting the proper opening, and most likely it will supply a template that you lay down over the countertop to center and mark a cutting line. Pre-drill a couple starter holes on your line and then cut the opening with a jigsaw. After cutting halfway, screw a brace into the bottom of the countertop to hold the cut-out in place while you finish cutting. Otherwise it'll start to sag and possibly damage the cabinet when it breaks free.
Most sinks are self-rimming so the rim rests on the countertop and supports the whole unit.
Run a bead of silicone caulk around the opening and drop the sink in place. Wipe away any excess caulk. If you've been doing the plumbing yourself, take time now to turn the water off. Remove the caps on the hot and cold water pipes and install shut-off valves that usually connect with compression fittings. If you're installing a dishwasher, put a valve with two outlets on the hot water stub-out.