Hi jaggybunnet. Most cases are made in China, and you are unlikely to find wiring instructions anywhere.
If your case has the usual front panel components you will have power switch, reset switch, power led and drive led. In the absence of any instructions the first things to identify are the switches. You should be able to follow the wires from the switches to the connectors. If you can't, get yourself a cheap multimeter like this one click here, but you should be able to find one in a local electronics or diy shop. Both the switches work as momentary contact when you press the button. Once you have got these right, you can identify the LEDs by trial and error. If you get the connections reversed, you won't do any damage, the LEDs just won't illuminate.