How do I make a patch?

[Daniel Foster <d foster handseek com>]

Hi,

I've just been having a play with the code and have implemented something
that was discussed on the list a month or two ago.  I'd like to make a
patch and post it up here for people to see, but I have no idea how to make
the patch file.  Can anyone point me at a tutorial or give me a quick
lesson?

-- 

Daniel Foster - daniel@34SP.com