Unfortunately, I can’t really help you learn to use your machine through the internets. That’s what Grandma’s are for.
If you’ve never used a sewing machine before, I highly recommend you either take a class or have someone who knows what they’re doing help you out. If you’re buying from a dealer, ask them to give you a quick lesson on at least threading the machine.
All machines are bound to be a little different, so even if you have used one before, take a look at the manual if you are using a new machine. I was threading a new machine wrong for 2 weeks before I actually looked up the manual online, and realized I had been skipping a step! Luckily, I wasn’t doing anything so wrong that it could do damage. It is possible to do something so wrong that you’ll break the machine before you even get to use it, so you might as well get friendly with the manual.
Big Tip #1: DO NOT FORCE THE HANDWHEEL. If you put the bobbin in, and it won’t turn, something’s wrong. Forcing it is likely to break something.