This is a Momentary switch. Meaning that it is only operating when you actually push the switch down. Used for something like a horn. Because this is an illuminated switch, you need to supply power to it, full time, for the illumination. They are the (+) and (-) terminals, self explantory. So then you need to decide whether you want the switch normally open (NO), or normally closed (NC). If it is normally open ( NO) , it will light up when you close it. So run the wire from where you are supplying the power to whatever you want to switch, to the C (common) terminal, and then run a wire from either the NO or NC ( most people would be using the NO) terminal, to positive on the device you want to turn on and off. You will have already run a negative wire to the negative terminal on the device . You will only use the NC terminal if you wish to turn something off momentarily, unusual sort of use.
EDIT--just re-read your post, and saw what you have bought them for, I think you bought the wrong type . For turning lights and such on and off, you want a toggling type. ie, push it once, turns it on, push it again, turns it off. You have a Momentary type which is more normally used for something like a horn. Only operated along as you are pushing it.