How can I automatically start an application (i.e. Firefox) when X starts?

It depends on which desktop environment you're using. Here's a good rundown:

http://gentoo-wiki.com/HOWTO_Autostart_Programs

Ok, thank you, but which d.e. does Puppy use?

Victor,

To auto start an X-Window program, put the program (or a link to the program) in the /root/Startup directory. Here's the contents of the README.txt file located in the same directory.


Any executable or scripts (or symlink to) placed in this directory
will be executed after the X desktop has loaded.

This is handy if you want something to run automatically.

You can easily create a "symlink" (symbolic link) to an executable.
For example, say that you wanted to run /usr/local/bin/rubix (a game)
everytime Puppy is started. Use ROX-Filer (the file manager) and open
two windows, one on /usr/local/bin, the other on /root/Startup.
Then just drag 'rubix' across and a menu will popup and ask if you want
to copy, move or link, and you choose to link.

Note, if you want to execute something at bootup and prior to X desktop
loading, edit /etc/rc.d/rc.local.

cheers,

Bill Thomson