You need to get a chemical to control the smell. Go to Walmart and look in the RV isle. Pull out the "trap door" and pour in a few ounces of chemical. On the back right there should be a screw top. That leads to the water tank. You need to fill that with water. Behind that should be an accordian type "pump". When you depress this it should transfer water from the tank to the bowl. That is how mine works, but it looks much older than yours and I have a pump out which it doesn't look like you have. If you don't you have to take the toilet off the boat and empty it manually. FWIW.