Do you have any knowledge about OTSvers?
Running version 11 shouldn't differ much from older ones so anything posted on those forums linked before may apply for the most part.
Also, what kind of server you want to run because theres lots of them ready to hit the download button and run them. If you want a custom server you may need to decide client version and look for a distro capable of running it.
For mapping you will need Remeres Map Editor (RME) and unless you want to actually want to change code (mostly c++) most of the time you'll work with .lua and some .xml file.
There is also item or sprite editors if you want to keep customizing your server much deeper.
To run the server you will need a website to create accounts with a database. Tutorial here.
Setting up your own OT server and website from scratch