Five years ago I wrote about the very small amount of Forkner Shorthand information available in the online world. The situation has improved a lot!
There are occasional discussions of Forkner in the shorthand writing forum on Reddit and their wiki has a page of online resources and recommended books to help you learn Forkner.
Although it is not as pretty as some shorthand systems, Forkner is one of the best choices for students who need to increase their writing speed as quickly as possible. Objective research conducted in the 1960s and 1970s backs up this claim.