Strip wire insulation off ¼” - using the proper size stripper tool for your wire gauge.

Insert wire into the appropriate hole and tighten screw to secure wire.
It is important that you choose a screwdriver that is not too large for the opening.
When tightening the screws once resistance is felt STOP - and then only 1/4 turn more to secure.
Over tightening will sheer off the copper wire and you’ll have to start again.

If you're having difficulty securing the wire try removing 3/8” of the insulation and fold the wire over - doubling the amount of copper.