Your incoming hot feed should connect to either one of the black screws, leaving the break off fin between the black screws intact. The connection to neutral connects to the silver screw and your switch leg connects to the brass screw.
I'm trying to install a Leviton T5225 combination switch and outlet. I have two pre-existing black wires in the box, two white, and ground. I'm trying to add a light, which I've also run to the box, adding one more white, black and ground. Which wires do I connect to which screws on the T5225?