Figures are fine. When you submit a package of code and documentation the figures should be in the /lal/packages/mypackage/doc directory. Please submit two versions of the figure: an .eps and a .pdf. We need both so we can build the documentation either with LATEX or pdflatex.
The syntax to use for putting in the figure should be something like this
\resizebox{0.5\textwidth}{!}{\includegraphics{myHeaderFileNameMyFig}}
Note. Don't include the extension on the figure file name in
the \includegraphics[]{} command. If you leave the extension off,
whatever method you use for building the documentation automatically
looks for the appropriate file.
Naming convention for figure files: Using the base name of the header file as the first part of the figure file name is a good idea. The reason: when the documentation is built, everything is LATEXed in the lal/doc/autodoc directory. There are hundreds of files there, and following this convention will reduce the probability of a name-space collision.