Please check out my longer 'ible about Old Sewing Machines here https://www.instructables.com/id/Old-Sewing-Machines-are-Hidden-Treasures/
Start by looking for an older, mechanical machine - they are great for learning on and pretty inexpensive. In fact, if you find one in a cabinet you can take it out of the cabinet and sell the cabinet!
Be sure to clean and oil the machine before sewing with it.
Check out books from your library on sewing basics and maybe start a sewing circle in your town so that many people can learn from each other :)