You start as you would any mind map. Begin in the centre with the main topic ie: Organic Chemistry, or i guess if you want to focus on a certain area, you can narrow it down to things such as: alkanes, functional groups, amino acids…etc. for the main topic instead. From there you’d just draw branches out, each relating to a major subtopic. Here’s a nice site to how to make a mindmap with some good examples: http://www.imindmap.com/articles/creatingFirstMap.aspx.
The basic principals all still apply to any mindmap, organic chem included. A good way to go would be to pick out key words and reactions and to put them in the mindmap. Don’t just copy and paste all of your notes onto the mindmap cos they don’t really work that way. Put lots of pictures too (if possible) and lots of colours, cos they really liven up a mindmap and most of all, have fun! Be creative! =)