You'll need to create your own "protocol" for this. You need to package up the data in whatever format you wish, as an array of bytes to send across the RF through VirtualWire. A good start would be to add a couple identifier bytes to the beginning so that you know what it is and what to do with it. You have a few options in that you could send actual values or a string, you'll just need your receiver to know how to read and parse the packet.