These look like an updated version of the old PT-04 "eBay triggers" I had years ago.
As Simon states, the transmitter goes on your camera's hotshoe, and the same channel needs to be set on both the receivers and the transmitter. The dip switches are obvious on the RX (receiver) units. On the TX (transmitter) they could be on its lower surface or even inside them (remove the cover).
The batteries that used to be provided with these things were often supplied wrapped in a thin clear plastic sleeve that covers the battery contacts. This is easy to miss, so check the batteries for it. Also, the condition of the batteries was hit-and-miss, so it's worth checking them with a battery tester or meter, and fitting new batteries if necessary.
Does the light on the TX flash when you press the test fire button next to it? If yes, great. If no, check the batteries in the TX.
Once you have the TX working as above, and the same channel set on your RX units, switch the RX units on and hit the test fire button on the TX. Did the indicator light flash on the RX (between the on/off switch and the dip switches)?
If no, check the batteries and move the units farther from each other - they can be iffy if the TX and RX are within a metre or so of each other.
If yes, you should be good to go.
Also, check that the TX is making good contact with the camera's hotshoe and that the RX is making good contact with the flash's foot.
These contraptions are not made to particularly tight tolerances, and very often a bit of a wiggle can make all the difference. ;-)
All in all, though, my guess (since you say you've had them for several years unused) is that you need new batteries.
