Turning them in makes them leaner, not out. The idle mixture screws are on the front of the carb, below and to both sides of the fuel inlet. But with only 10 miles on it, you're not going to get an accurate read, and it's better to be a little rich on break-in than a little lean.

You need to turn them evenly, so best thing to do is to turn them clockwise until lightly seated, counting the turns, then turn back out to the same position. If one screw is out 5 turns and the other 6, back them both out six turns then start the car and let it warm up completely. Make sure the choke is fully off, then turn each screw in half a turn at a time, listening to the RPM.