You pop off the plastic cover to the thing on the back of your seat. I never even knew these things came off. I took the screw out in this photo because I was cleaning it off. Apparently it is a major trap for pee from a 5 year old that has a really bad aim. Gross! Just pop off the plastic cover so you can see the screw head.
(sorry, I didn't get it as clean as I wanted for the photo, and I scraped the crap out of it as I didn't realize there was a nut on the underside so I was trying to pop it out insetaed of unscrewing it. oh well!)Then reach around the underside of the toilet and there will be the bottom half of the screw hanging down with a nut attached. I didn't realize in this photo my nut is missing because I took it off and didn't put it back on before I took the photo but there will be one there. (there was pee on the underside of the screw too) Just grab the nut and hold it tight while tightening the top part of the screw with a screwdriver.
Who knew it could be so easy? I'll be removing mine regularly for cleaning.
I'll post more about becoming the "queen of my castle". I have a feeling I will have to learn more as Ben will be gone a lot this year for rotations and I'll be on my own for repairs. This could get ugly!