Raid the linen cupboard or the charity shops, get yourself a few old sheets/pillowcases/curtains, and get the feel of the machine by sewing these into simple bag shapes, cut the legs from old trews and stitch one end shut to make pouches and when you get a bit more confident add a drawstring to the open end. Have a scoot about on the 'net and learn how to do the different types of hemming and some different seams.
Things to have before you start are polyester sew-all thread, different needles for light and heavy fabrics, a decent scissors and seam ripper, tailor's chalk for marking out and a measuring tape (fabric or plastic),
and some good pins for pinning your work together before you stitch.
There are a lot of very good videos on youtube and other such sites, and some local authorities run really good evening classes for beginners, these are really great because you have somebody right there who knows all about what you're trying to achieve; it can all seem a bit daunting at first but it becomes much clearer very quickly.
Don't be afraid to ask as often as you need here, and let us know how you get on. It really is a very satisfying skill to have even on a very basic level.
