Hello, I'm a 41 yr old married man... I'm trying to teach myself to sew

I'm very creative--have a degree in graphic arts.
I think--I can learn it. I purchased a nice machine a month ago..... a JANOME it's nice Computerized. I have made some simple things to get use to the feel. I have not sewn since 8th grade

I got a few patterns from Walmart for dog clothes. But a few of them are very

?? What does the term... Cut 2 on Fold mean? Or Cut on fold? I have a vest harness pattern... When and how do I add the strap for the D ring? I want a lining in the vest. I wanted to turn it inside out and back? Make it look nice? Can someone explain?