location question

How do i set it up to randomly choose a spot on the map not chosen by me 

Right now KOTH runs in zones you create (/koth create <name> where you stand). To get variety, create several zones around the map and add their names to "KOTH Automatic event schedule random from list" in the config, and the schedule will pick one at random each time. Fully random positions anywhere on the map aren't supported yet, but I've noted it as a feature request.