We will quickly go over a few points though just to clarify. Lets start with .onion domains. Basically what a .onion domain is, is it is a pseudo top level domain which is used for anonymous surfing on the Deep Web via the Tor network. The .onion domain is a 16-character alpha semi-numeric-hash These are not domains that are part of the ICANN registry and you cannot go out and buy one at a typical domain registrar such as Godaddy, even if you wanted to.
Basically the procedure to set up one of these .onion domains and hosting is very simple but it is too lengthy for us to go into, in detail on this eBook. It is covered quite extensively on the TorProject.org website and here is a great tutorial which will walk you through every step in getting your own private .onion domain set up. Follow this link
Once you have installed your own server, (which is recommended) and you have installed the Tor browser software, Tor automatically generates the .onion address for your website for you. If you follow the instructions on the website above (which is recommended), pay very close attention to the details and do everything that the site tells you to do. It is possible by utilizing this .onion domain also, to instruct Tor to give your website a brand new identity, at the click of a keystroke.
Getting a .onion domain is not only free (they are automatically generated by Tor), but it is simple once you have completed the basic server installation procedure. If you are not familiar with servers find a friend or a tech whiz who can walk you through it. As with everything computer related, it is fairly difficult if you have never done it, but after you do it once, it is basically a breeze. The next time you generate a new address for yourself will take you only seconds.
For more specific tutorial to to: http://www.makeuseof.com/tag/create-hidden-service-tor-site-set-anonymous-website-server/