Toilet seats are easy to replace or repair.
Lower the seat cover and pop up the screw covers at the back and remove the two screws that hold the seat to the bowl.
Lower your new seat in place, careful to align the holes.
Insert the new screws with the nuts on the bottom (bowl side) and tighten with a screwdriver on the top side and a small wrench on the bottom.
Despite all that is associated with it, I think you will agree that toilet seats are one of the most important and needed parts of your plumbing system. Most are well built and reliable fixtures but with their everyday use you are going to have problems sooner or later. Most people are intimidated and confused by the way they work. But, it is best to have a little understanding of how they are repaired. Toilets have not changed much in the basic way they operate since their invention. So many basic repairs can be done with very little repair skills and you will not have to call a plumber.
Toilet seats are repairs you can do yourself.