How do you extend an outlet in the backyard?

Question:So I got 12 gauge Romex wiring for my outlet. I want to exten the location of an outlet previously on a wall outside the house. This outlet has two blacks coming out of it (power wires, one for each outlet), and two whites, along with one ground. Now with these wires, I'm taking one of the black wires and connecting it to a switch, and from the switch comes another black wire which extends to the location I want the new outlet to be for. As for the white wire, it will connect to the white wire of the extension and travel with its black wire along to the location of the new outlet. Yet now the problem is, the switch is only connected to one of the plugs in the outlet. I am still left with a black and white (for the other plug of the outlet) which I do not want to waste. We still want to leave a plug for other purposes. What can I do with the remaining black and white wires? Can I use them to create another outlet somewhere else? If I did, what would I do with the grounds?

Answers:
you want both sockets to switch on the new outlet?

if not run the black and white spares over to it, or use it to put another outlet in elsewhere, make sure your romax is the type that you can bury,,

if you do not want to use the wire, just wire nut each wire ( Not together ) and tape also, and stuff them back into the box