How do i create an organisational chart in numbers

Numbers is for spreadsheets. Org charts are graphics. You can do graphical stuff in Numbers but why do you want to? Which leads me to the question:

Can you be more specific about what you want?

You can use circles, rectangles, and lines to create an org chart. You could use the tabular structure of Numbers (using cells within a table or using multiple tables) and then add a few lines to connect the cells/tables. Neither of these are using the strength of Numbers but it is possible to do it.

I think it is a great idea to use Graphviz for this kind of thing as it is very powerful and can be created from a text file which then makes a postscript or other image you can include.

I suggest visiting:

http://www.graphviz.org

to see how this too could help you.

I don't really think Numbers is the best tool for this job.