A beginner that could use a few tips on wiring my first circuit involving relays
The pictorials at the bottom of your question shows how it is wired. Supply the receiver with an appropriate voltage. 3rd from the bottom shows it simulating a momentary switch. 

It appears to have an AMS1117 type of semi-LDO regulator so more than 5V would be appropriate given the 4.5V relay coil. 

If you get the power polarity wrong, even briefly, it will almost surely destroy the receiver instantly. 

The three connections go to a mini signal relay type UD-2. 

"ON"(sic) means "Normally Open"

"COM" means "Common" 

"NC" means Normally closed, which you probably don't need. 

Between "COM" and "ON" is a contact (effectively a switch) that is normally open and closes when the relay is actuated. No voltage is output, according to the diagram shown. 



Do not use the relay to switch mains voltage. If the device you are controlling is connected to the mains without isolation, even though it is switching a lower voltage,  you may create a safety hazard with respect to the isolation between your supply and what the relay is switching. For example, a switch in a mains-powered device that lacks galvanic isolation between the switch and the mains could potentially put mains voltage on the power supply leads, particularly if it got wet. There are insufficient PCB clearances for such an application regardless of the relay rating. Seek qualified local advice if mains voltage (or more than about 24V) is involved anywhere in the circuit.