I claim not to know how to use my machine at times too.
Not all machines are the same, some need adjustment too. If your machine is out of whack, misbehaving, it could become quite frustrating. Look for a small shop that works on sewing machines if the manual by itself doesn't help enough. I've found such places to be quite helpful, esp. if you need a part for your sewing machine to work well. If it has been sitting for a while it may need a tuneup.
Start small, easy projects. In fact if you have some old worn out sheets or any cloth scrapes practice some stitches on it. Make sure you have bobbins and extra needles. In fact cloth, bobbins, and needles would be good to keep on hand.
I used to sew a lot, but as the price of cloth and patterns went up, I found it much easier and less expensive to shop sales. If I had separate spot in the house where the machine was always ready and available I'd have done much more sewing.
My oldest son, when he was in middle school decided he wanted to sew himself a kite and windbreaker. He is always making something. I explained how he should find a pattern, follow it, esp as he'd never sewn before. Nope, he had something in mind, said he knew what he was doing, willing to spend his own money on materiel so I turned the machine over to him. He did learn how to use the machine, the kite did fly, the jacket he wore to school a few times. I wasn't so sure about the jacket going to school, it was very interesting to say the least. He learned that bodies aren't 2 dimensional and that it is better if you give yourself room to move your arms around, etc. Point is, even with no prior experience or teaching (he really didn't want help in any way) someone could learn to fasten 2 pieces of cloth together and come up with something and with time perfect the skill.
I did dust off the cobwebs a several years back when my oldest daughter got married. She couldn't find the perfect dress. She liked part of one dress and part of another. Knowing I could sew it as she wanted (combining 2 patterns), and save much money it was worth pulling the machine back out. Came out great, even if nerve wrecking when I realized I'd better have it right the first time as it was too late to find another dress or try again if I messed up.
Sewing machine is back gathering dust.