((((HUGS!)))) I would love to offer more than encouragement on how to do the miter corner on binding, but i'm still struggeling with that myself. I do okay to sew down the front side but when I have to flip to back side and do the miter I have issues.
Don't let the people at the senior center get you down. Maybe you could go to one of the LQS and get assistance from someone. I have notice that most of them have at least one day a week where you can bring your unfinised projects in to work on and get help. Good luck.
Some of the online tutorials are great on Youtube. I have gotten a lot of help from some of them. Just do a search. Check the tutorials here on the site to.