1913SF, eBay, no signal

So I bought a Dell 1913SF19" LED TFT 60Hz VGA Monitor (this is what eBay says it is). It didn't come with any cables so I went and bought some and plugged it into my pc. I turned the power on and it said " Entering power save mode" then when I press a button it says " There is no signal coming from your computer. Press any key on the keyboard or move the mouse to wake it up". How do I fix this? I don't really want to throw it away as it would just be a waste of £24.