graphonline/en/wiki/pub/skins/pmwiki

This directory contains the files to display pages in PmWiki according
to the default layout.  

==>Don't edit these files directly, as you may lose your edits the
next time you upgrade PmWiki!

Instead, copy the files to another directory in pub/skins/ and edit
them there.  You can then configure PmWiki to use your modified layout
files by setting the $Skin variable in your local/config.php.  For 
example, if you copy your custom skin to pub/skins/custom, then you 
would set
   $Skin = 'custom';
in local/config.php.

The files in this directory:
    pmwiki.tmpl   -- the default template for page layouts
    pmwiki.css    -- PmWiki's default css
    pmwiki-32.gif -- the PmWiki logo

If you just want to change the logo, you can do it by setting $PageLogoUrl
to the url location of your logo.