fix 3 socket and 1gang switch on a 8 module switch plate, connect mains to the switch common, connect the branch to red terminal of the first socket and loop it to the two sockets. connect the incoming to the first black terminal of the socket and loop it to the two sockets. connect incoming black green to the green terminal of the socket and loop it to the two sockets. cover the socket to the wall and put ON the switch. Your socket is ready.