mod_rewrite issue

Hi Gang -

So I went on with the latest installation of G3, migrated old G2 albums succesfully, etc.
But now when I try to set permissions on albums I get"

"Oh no! Your server needs a configuration change in order for you to hide photos! Ask your server administrator to enable mod_rewrite and set AllowOverride FileInfo Options to fix this."

So, I understand that I need to modify my .htaccess file, but not sure what lines to add there. Anyone has an idea what code should I add?

thanks!
g