Fortunately, upgrading to 0.3 should not be too hard. First off, replace your
old copy of photo.pl by the new one. Then, delete all the *.inc and *.php3
files from your web directory (in the web server's document root), and copy all
the new files in the web directory to the web server's directory, but *not* the
pics subdirectory (that would erase your pictures)! Re-edit the config.inc
file: new configuration options have been added.

Finally, you need to update the database schema. Simply type:

mysql -p <your_db_name> < upgrade-0.3.sql

For example:

mysql -p photo < upgrade-0.3.sql

You should be all set!

(For a new security tip, check the end of the INSTALL file.)