Looks like early 60s. You should be able to find a manual online, some free, some not. Threading isn't hard. Do you have anyone with a sewing machine who can show you? That's a pretty standard pattern on that one. Get rid of that thread. it looks rotted. You don't want to jam the machine with it.
The thread comes from over the back of the machine, though the top right guide, down between the plates on the tension, under the little spring (you must catch the spring) and up to the dohicky that moves up and down when you stitch. Then down the front left through the thread guides. Most needles thread from left to right. One of mine is front to back and one is right to left. The needle will have a deeper groove on the side the thread enters. Is your bobbin vertical underneath or laying horizonally? I'm guessing vertical. Those are trickier to thread than the top threading. The thread comes off the bobbin counter clockwise and you have to hear a little click as it the thread reaches the correct slot. Then the bobbin goes in with the little flange pointing upward.