A couple of possibilities
Since you're new at this, I'll start with the easiest one: Are you sure the intake seacock is open? If it is, are you acquainted with the "dry"/"flush" lever (on some models its a knob) on the toilet? When it's in the "dry" position, no water comes in...the pump only pushes the bowl contents out. Turn the lever the "flush" and water comes in. If neither of those is the answer--and it's worked before, something is preventing the intake hose from priming. It may be that the dry/flush valve has failed and is stuck in the "dry" position--in which you'll need to replaced it. If you've anchored in shallow water and stirred up sand, and used the toilet, sand in the pump will do it--in which case you need to take the pump apart and clean it. Or anything that's allowing air to get into the line will do it. Check out all of the above, and if you don't find it, get back to me. (Btw...using all caps is the online equivilant of SHOUTING...and it's hard to read.)
