The first time you thread a sewing machine, the path looks like a maze. Wires, slots, levers, a take-up arm that moves on its own. Miss one guide and the machine stitches loose loops or jams the needle.
Jann Newton from Newton Custom Interiors walks through it on a Singer Heavy Duty in this video. The exact diagram on top of your machine may differ a little, but the path is the same on most front-loading machines: spool to upper guide, down through the tension disks, up to the take-up lever, down to the needle, then pick up the bobbin thread through the plate.
Pull out your machine's manual once for the spool direction and the threading diagram, then follow along below. Once threading clicks, our guide to hemming pants is the natural next project, and sewing a button by hand covers what you can do without the machine running.
Threading a machine is fiddlier than threading a needle, but the job it does is identical. If the needle work itself is the unfamiliar part, how to sew by hand covers threading, the tailor's knot, the backstitch and how to tie off so it holds.