Firstly you must replace the original switch with a two way fitting. Use razor blade or utility knife to cut paint closely around edge of plate to free it.

How To Replace A Standard Switch With A Dimmer Switch For Dummies
How to change a light switch cover. Unscrew and remove the ground wires separate them and isolate the one that belongs to the same cable as the live hot wire. Connect the switch to the box at both the top and bottom. Remove the switch plate cover. Remove switch cover plate. And after that you should link the two with 1mm 2 three core and earth cable. Take your new glam light switch and follow my above guide as to where the 3 wires need to be secured in the new plate.
This is for sure an indication to go ahead and replace the two while you at it. Now you have one uncapped black wire a white wire and a bare ground wire. Use your insulated screwdriver to gently unscrew one at a time all screws holding the three wires in place. Remove your old switch plate. Then disconnect the wires from the screw connectors on either side. The new light switch will connect to the box in the wall with the two screws provided with the new switch.
Untwist the white neutral wires in the box and cap the one that belongs to the same cable as the hot wire you capped. Once the power is cut remove the switch cover and mounting screws with a screwdriver and pull the old switch from the wall. If cover plate doesnt come off easily it is probably being held in place by several layers of paint. Then youll need to install a new two way switch at the second control point. To replace a light switch start by disconnecting the power to the switch by shutting off the breaker for the room. Find out how to replace your light switch faceplate covers in your apartment.
Place the new wall plate over the new switch and attach it to the wall with the screws that came with the new cover plate. There will be times though that a light switch do decide to malfunction and look sort of worn out looking. Start by running the cable between the two switch positions and installing a mounting box at the new switch position.