DokuWiki can convert text smileys to their graphically equivalent. Smileys images are stored in the lib/images/smileys/ directory and configured in the conf/smileys.conf file. You can add your own smileys by creating a conf/smileys.local.conf file and placing your additional smileys in there. Make sure the images are readable by the webserver. It is possible to add smileys to conf/smileys.conf file, however this could result in your changes being overwritten when upgrading Dokuwiki. Note that you can't use # or $ in the configuration file.
If your newly added smiley does not appear in your edit toolbar popup, it is almost always a problem of caching. You may have to purge the cache, then refresh your page.
The following smileys were created by DokuWiki users, using a similar style the default ones. If you like them place them in your smiley directory and adjust the config file.