Electric practice - How to use a digital multi-tester (How to check the ground line)

Using the AC (alternating current) measurement method of the digital multi-tester,
1. Heart phase, how to find mid-line (Hline - ground potential difference 220 V / Neutral - ground potential difference approx. 0 V)
2. The ground line check method is made by video. It's not enough, but I hope it helps.