The first main thing is how to thread your machine(s), since that does tend to be pretty similar from one machine to another but with slight differences. So I’d learn how to do that for your particular model(s), how to wind a bobbin and get that all hooked up.
Then just pick up some scrap bits of fabric and go to town with the different stitches and features and see what happens! If something goes wrong, search online for the specific symptom and you’ll learn a lot that way (this is how I learned how to adjust tension back in the day).
Do you have a manual for either machine that takes you through the different stitches etc? If not you’ll probably be able to find a PDF version online if you search for the model number.