where to add filetypes

[Rufus R Jones]

I open up options/downloads and I have no
filetypes showing and no place to put them.
I click on plugins and none of them are showing
although about:plugins shows them all.

(I don't care about the plugins right now, only
concerned with adding filetypes)

The Realplayer plugin doesn't work and I would
like to add it as a filetype helper but there is
no place to put anything as far as helper apps is
concerned.

What to do??????????

Thanks