The symbol that looks like the number "8" laying on it's side is the infinity symbol. It's next to your focus ring on your lens.
I don't know the particulars of you location and shot. But here is what I would do:
Set your camera on a tripod
Set your ISO to the lowest number
Switch your camera to manual
Meter of a bright portion of the sky.
For a landscape scene by default I would set the camera to F8 or F11
Adjust your shutter speed of the meter. Depending on what you see, you should be aiming for at least a few seconds, if the shutter speed is faster than you like, set the aperture to higher F number and adjust the shutter speed accordingly.
As sabath said, switch your focus to manual.
Prefrably shoot in raw, as you never know what white balance you could really get with a lighting strike.
Make a few test shots and check if the image is blown out anywhere or too dark. The cameras overexposure overlay is great for this, as is the histogram (with out getting into histogram color channel issues).
This is just the way I would shoot, not knowing what exactly you up against.
Take it all with a grain of salt as I have never shot a lightning bolt (they are extremely rare where I live)