There are various kind of machine sewing, each one used for different applications. Below, we'll just focus on conventional sewing machines (as opposed to serger, cover-stitch, or embroidery machines)
Conventional Sewing Machines
A conventional sewing machine typically has one top stitching thread (pulled from on top of the machine) and one bobbin (used to secure the backside of the fabric). The two threads work together to find your fabrics. E-textiles can be sewn using sewing machines, but can be difficult because they break. Luckily, many e-textiles practitioners offer guides to the yarns that work in both the top stitch and/or bobbin.
For a general introduction of sewing, you can watch this video on YouTube
Youtube is also a great resource for learning how to implement the other techniques (fabric manipulation, quilting, some couching/embroidery, etc.).