How to measure exposure value and white balance (specifically gray or white) with gray card in studio flash?

When measuring the exposure of the gray card, face the lens with the gray card, then measure the light of the gray card with the photometry function in the manual exposure mode, and then determine the combination of aperture and shutter. Of course, the placement of the gray card will affect the exposure effect during actual shooting, which requires more experience.

White balance is to take a photo with a white face, and then adjust the white balance with reference to the color of the whiteboard in post-processing, and then take this as an example to deal with the white balance of other photos in the same scene.