with no prior experience, i would like to refinish some inside wooded doors i.e bathroom, bedroom doors. They are scratched and a cpl of them have what appear to be white, round spots near the bottom...mildew? (they dont wash off). thanks.

It's easiest to work with them if they're removed from the hinges and laid flat, but you don't have to. You probably should remove the doorknobs, but you don't absolutely have to.
If they are painted, just make sure they're clean and dry and then paint. You may need to sand the scratches first. Usually gloss or semi-gloss paint for doors and woodwork is preferred.
If they're stained and varnished, it's more work. You'll probably need to remove the varnish with a remover product. Then sand the scratches. Then stain, then varnish.
Another option: interior doors are very inexpensive to replace. You can use your existing hardware from the old door. They come in standard sizes, already finished.