If you’ve just loaded the bobbin, you’ll see one thread, but the majority of the time you’ll start with both the needle and bobbin thread visible. Pull the thread to the back, making sure they’re going under the presser foot.
Next thread the sewing machine. Again refer to your manual for specifics.
Put the thread through the hole in the needle, front to back.
Sewing machines make stitches by taking the top thread that runs from the spools through the needle and looping it with the bottom thread from the bobbin so that they interlock.