See the plugin in action here. The sample page shows all the styles available with the plugin.

A simple usage:

{{icon>home}}

Some more complex uses:

{{icon>home?24&circle&padding=10px&background=#DDD&color=#CCC}}
{{fa>home|My Home}}
{{fugue>user?24}}
{{silk>anchor}}
{{flag>en}}
[[:wiki:welcome|{{fa>home?24|Welcome to DokuWiki}}]]
[[https://github.com/LotarProject/dokuwiki-plugin-icons|{{fa>github-square?24|Icons DokuWiki plugin on GitHub}}]]