How to establish a RF link

Hai,
I am newbie to RF communication. I want to establish a RF link between my PC and a remote location. All I want is, when a relay/switch is operated,I want another relay/switch at remote location to be operated as well. How do I select transmitter/receiver.By doing the above job I also want to know how RF communication works exactly. Could any one please help me with this

Thanks

Hai, I think I should be more precise about this application

All i want to is to control a lamp from a remote location without any wires. Whenever my master ckt send a signal (ON/Off), I want a relay at remote location to be ON/Off according to signal. Some thing like can be done with a led and a photo transister. But I have some problems like direct contact and distance between master and slave(abt 1-2 meters). How could I accomplish this task with RF/any other wireless communication

Thanks

you try rfsolutions.co.uk