Here is an example of a long exposure, and lots of patience, photography. The method is pretty simple, keep exposing for as long as it is possible on your camera and hope the lightning occurs during the exposure.
Some cameras have a “bulb” mode which allows for almost unlimited time photography. However, you need to keep in mind the aperture needs to be F8 otherwise you will overexpose the photograph. Using a “bulb” mode you may be lucky to capture multiple lightnings into one frame.
The lightning usually is very bright and even at F8 will make a clear line in the capture. If it is very dark, as it was in this case more adventurous settings may be used. In this case I have opted for 30s at F4.
Naturally this is where a tripod is a must, and a remote release strongly recommended. I have used 2s delay on my camera at the time, which also may work for you.