Greetings and Congratulations on your new boat! You have some great times ahead of you. As for the "cannot get the waste to pump out" there are several possibilities. The simplist one is that your boat may be fitted with a "Y" valve in the outflow pipe and that valve may be pointed in the wrong direction. The outflow pipe from the holding tank should be readily visible. If the pipe does not go straight out but divides and goes through a valve (the "Y" valve) there will be a plastic lever that will select whether the effluent goes straight up and out or goes through a macerator pump and out through the side of the boat. The lever is marked with an arrow which will show the direction of flow. The shape of the handle itself is not intuitive so look for the arrow and make sure it points to the pipe that is going up to the suction.
If that is not the problem other things to try include: 1) Try more than one pump-out station as sometimes the vacuum is to weak and can't pull the slurry out, 2) Add some water to the tank before you go out so the slurry in the tank is as thin as possible for pump out at the end of the day, 3) Stick a wire down the pump out opening carefully to dislodge any solids that may be stuck up against the pick-up tube, 4) Make sure the vent to the tank is unobstructed--even insects can plug this vent up, 5) There are some additives at chandleries like West Marine that can be dumped into the tank to help with the odor and to help break down solids. I haven't used those since having a houseboat years ago but I know they exist.
Keep in mind that the marine septic systems are very fragile and they are prone to clogging (see multiple posts on this site and elsewhere) and you need to be very careful of what is put into it. It sound s a little OCD but placing a sign by the head that lists the contraband flushies is a good idea. Guests may have no clue that there is anything wrong with putting a wad of Kleenex down the toilet. Some boat owners go so far as to ban anything from entering the head that was not eaten first! It's your boat so you can make the rules.
