How to make the connections to the 1 channel optocoupler relay module?
The signals on the left are the input side and the signals on the right are the output side.

Ok so now it is clear that you have a module rather than just a relay. The module has additional circuitry on it for driving the relay. Based on this the input pins are as I put in my original answer:


DC+ - Positive logic supply voltage
DC- - Negative logic supply voltage (a.k.a ground)
IN - Input control signal - the thing that tells the relay whether to be on or off.




On the output side a bog standard switch naming is used:


NC  - Normally Closed (Connected to COM when relay coil off)
NO  - Normally Open (Connected to COM when relay coil on)
COM - Common pin of switch




Your relay operates as a DPST switch as shown in the diagram below.





You need to apply power to the DC+/DC- pins (such as a battery), and then use the IN pin to control whether the relay is on or off. Connecting the IN pin to DC+ will turn the relay on (connect NO and COM), and connecting the IN pin to DC- will turn the relay off (connect NC to COM).

You may need to add a resistor in series with the IN pin - i.e. don't connect it directly to DC+ or DC-. A 1k resistor will suffice. It is not clear from the description whether or not this is actually necessary as the information on the listing is a very bad translation.