I have a very similar saw, with a table extension on each side. It looks like the front guide rail has been put on incorrectly: it needs some spacers on the bolts fastening it to the table (spacer between the rail and table) so the fence can properly hold onto the rail, with its little viewing window lined up over the yellow measuring tape. Also, technically that rail should be adjusted to the right, so that the measuring tape has it's zero lined up with the blade, even though I don't trust those measurements. Also, looks like you're missing the rear guide rail.
Here's the manual if you don't have it. On page 6, the spacers are part R, rear guide rail is part E:
https://www.manualslib.com/manual/480033/Craftsman-113-298051.html?page=6#manual
If you don't have those parts, as said above, some sort of straight edge with clamps should work fine... maybe even better than the original fence system lol, which can be a pain to line up.
Hope that helps, good luck getting it into action!