Hi Mehrdad ,
The best way to get started is to install the LaTeX class and examples in your
texmf folder (~/Library/texmf/tex/latex on Mac OS X,
/usr/local/share/texmf/tex/latex on other Unix-like operating systems; if the
folder doesn't exist, then create it). When done, open up a terminal and type:
sudo texhash
When done, Open LyX and select Tools->Reconfigure. Restart LyX.
To use the aaai style, create a new document in LyX using the "article"
document class.
To the preamble of your document (Document->Settings->LaTeX preamble), add the
following:
\usepackage{aaai}
\usepackage{times}
\usepackage{helvet}
\usepackage{courier}
For the bibliography, choose Insert->LaTeX Bibliography and specify which
BibTeX database you will be using. To ensure that it uses the right style,
find aaai from the available options and select it. Press Ok.
Then, start writing. You're very lucky. Aaai is implemented as a LaTeX
package (rather than as a stand-alone document class), which means don't need
to create your own custom layout. The \usepackage{aaai} command will ensure
that the formatting complies with the publication specifications.
If you want additional information, take a look at the
"formatting-instructions.tex" file which came as part of the AuthorKit. It has
some good information on how to get started. If you are going to be using LyX
long-term, it will also help you become comfortable looking at LaTeX source.
You don't need to be a LaTeX guru to use LyX, but understanding the basics
opens a whole new world of what you can accomplish.
If you're interested, I've written a couple of articles that explore this more
in-depth:
Customizing LyX: Create an NIH Grant Proposal
(http://www.oak-tree.us/blog/index.php/2009/11/02/custom-lyx-nih)
Customizing LyX: Character Styles and the LyX Local Layout
(http://www.oak-tree.us/blog/index.php/2009/11/14/customize-lyx-character-styles)
Best of luck with your paper.
Cheers,
Rob Oakes