Confused about thread size
Hello, my name is Kyle and I am new to fly tying, and becoming addicted. I was given an assortment of fly tying equipment, including vise, tools, thread, hooks, beads, and other various material. I have been watching a bunch of youtube videos and it seems when they wrap the thread towards the back of the hooks, it is always very wide and lays down very flat and completely covers the hook. I know if you unwind the bobbin it will widen the strand, but I never see them do this. Most of my thread is 6/0. For right now, I tie mostly midges. Is this thread the wrong size for midges? I am not sure which sizes of thread are bigger and which ones are smaller. Also, i'm not sure what size thread you should use for various applications. I was given dozens of spools of 6/0 thread, so that is what I have been using for everything. Is it necessary to change thread size for various applications? for example, I want to start tying pheasant tails. Can I use the 6/0 thread that I have, or will I need to buy a certain size for this fly? If there is a chart out there with thread sizes, that would be great. Any help is appreciated.