well first you plug an audio signal into them, whether its XLR or 1/4" jacks. Once its plugged in and the audio signal is going into them, i suggest you turn them on. Next, make sure the mutes are not engaged, there is mute high and a mute low, those are for service purposes only so have them both off.
Finally. Turn the volume up. You'll see on the back there are room correction adjustments you can make, don't worry about those for now. Right now you said you just want to make them work. so if you follow those steps you should be ok.