[OS X Emacs] Configure Hard Wrap Option

[Karim]

Hi,

I have been a long time user of TexShop for editing TEX files. A friend of mine
recently suggested I use Aquamacs as it can do TEX and much more...

I am trying to set the default width (number of characters) for the Hard Wrap
Option and I have no clue whatsoever how to do this or even if it is possible.
It seems it is currently set at 73 and I would like it to be 80...

Any suggestion is welcome.

Karim