For a testing dojo there is little you need to prepare.
- a meeting room large enough
- access to a computer
- a video projector so everyone can see what's happening
- pen and paper, a flipchart or a whiteboard to take notes
A meeting room with a computer and a projector are usually available. Pen and paper for note taking are easy to organize. You will get more benefits if the notes from the session are clearly visible to everyone in the room, especially after a mission to learn about note taking. You can look at tools like Rapid Reporter or a commercial tool like BB Test Assistant - in case you already use it at work - to take session notes directly on screen.