Two of these options allow users to upload an avatar from their machine or a remote location (via a URL). If you wish to enable this function you should first ensure the correct paths for uploadeable avatars is set in Admin -> General -> Configuration -> Avatars. By default this is images/avatars but you can set it to whatever you like, just ensure the configuration setting is updated. You must also ensure this directory can be written to by the webserver. Usually this means you have to alter its permissions to allow anyone to read and write to. Exactly how you should do this depends on your ftp client or server operating system.

On UNIX systems for example you set the directory to a+rwx (or ugo+rwx or even 777). This can be done from a command line on your server using chmod or via your FTP client (using the Change Permissions, chmod or other Permissions dialoge box, see your FTP clients documentation for help). Most FTP clients list permissions in the form of User (Read, Write, Execute), Group (Read, Write, Execute) and Other (Read, Write, Execute). You need to tick all of these boxes to set correct permissions.

phpBB 2.0.4 includes support for using uploadable avatars on systems running PHP in safe mode. If this applies to your hosting service you will need to create a sub-directory called tmp in the directory you specified for storage of uploaded avatars (by default this is images/avatars as explained above). Give it the same access rights as for uploadable avatars above.