Avo CT160 tester how working?

Hello friends
Recently, I bought a NEW Avo ct160 which is from military and was in the shelf as a reserve tester. As I said, it is new and in very very mint condition. Unfortunately, as you all know it is a complicated device and I can not work with it. Can someone send a clip or anyway show how to test a known tube step by step? This is my first tester. I am a very novice in vacuum tubes. I really need step by step guide. Thank you all.