Jane,
What you have is a typical HA-1 / 15 clone. I do not have a manual specifically for that machine, but if you go to the Yahoo Japanese machine group they have a free generic manual to download.
If you have a Singer Mdl 15 manual it will thread the same as that.
Here is my HOTHER follow the red thread. Looks like your machine has a hook on the top tension rather than the bent arm as my machine has. Other than that the threading is the same.
With the presser foot up;
>Come off the spool to the thread guide on the rear of the face plate.
>Down to the top tension from the back side under to the front side, making sure the thread is between the discs.
>Around the bottom of the tension, up behind the little hook or the bent arm, then over the hook or arm then under the thread check spring then up to the thread take up lever.
>Through the take up lever eye from the rear to the front, then down to the thread guide on the face plate.
>Through the face plate guide to the guide on the needle bar.
>Then through the needle from the left to the right. Needle mounts flat to the right.
Joe