In the VirtualWire download directory there is the VirtualWire documentation in PDF format.
If I understand you correctly you want to be able to push a button connected to the transmitter Arduino and then have the receiver Arduino operate a motor or whatever?
If so, then you will want to look at how to get the transmitter example to accept an input and send some data over the wireless link as a result. And then look at how to get the receiver example to perform an action when it gets the data.
--Phil.