Add new Financial Dimension backing entity

Under General ledger -> Setup -> Financial dimensions, open the Financial dimensions form.  If you create a new dimension there is a list of 'Use values from'.  These are the backing entities that you can use values from.  I had a project to add something to this list.  

Rather than type everything out, here is the link to a post I found that gives a perfect description of how to accomplish this. 

Thanks!