It's easiest if you take some time for a short introduction in the basics of sewing. That might spare you a lot of tears and head aches.
I never did and it took me a year of fumbling and cursing my sewing machine before I realized that the thread kept tangling up or the needle kept unthreading because you're supposed to put the take-up lever in the highest position when you stop. Seems so silly now, but hey, if no one ever told you..

Read the manual for your sewing machine. If you don't have a manual anymore, you can find it on the internet. The manual will give you a lot of important knowledge.

And of course You tube comes in handy here. There are a lot of videos on the basics of sewing (and for that matter every other craft as well).
Try these..

If you prefer written help, there are lots of websites. Try SEW-lutions. Or go to your local library or bookshop. There are books on sewing in every language I imagine. I enjoy having this one around the house - close to my sewing corner.