To add a custom logo and make the logo a clickable link you have to add a <link> and a <logo> tag to your <defaultFrontendSetup> in the main configuration of the Poolparty Frontend.
e.g.
<defaultFrontendSetup>
...
<link>http://poolparty.punkt.at</link>
<logo>http://ppserver.punkt.at/PoolParty/images/logo.jpg</logo>
</defaultFrontendSetup