Connect to second Wifi network using dongle

I have a Macbook Pro running Yosemite (10.10.1) and an Asus wifi dongle.

I would like to connect to two wifi networks. One is a normal home/office/hotel/conference network with a connection to the outside internet, the other is a local internet with two other machines on it (a windows tablet and a PLC controller).

How do I do this?

(I can't even tell if the wifi dongle is being recognized, but it's supposed to support Mac. When I use it with the windows tablet, I get a "Wifi" and a "Wifi 2" option, and I just set each to different networks)