I have never had a manicure done to my fingers
They are usually performed in a nail salon, but you can do it at home by yourself.  I've seen some nasty infections from nail salons that are not sterile.
I can imagine. I have never had a pedicure either
Basically they would file the nail, clip any dead skin, push back the cuticles, massage, and apply polish - they would do the same to the feet as well if you got a pedicure.
My nails are usually in good shape, fortunately.
That is really good.  With skin being manipulated and trimmed, there is always the risk of infection at the salons.  So if you can do it at home, that's probably best.