exactly which text of the infobox page should be translated?
create a site called Template:Infobox_Objectclass and copy and paste the
text from the english
http://wiki.puredata.info/en/Template:Infobox_Objectclass into it. then go to http://wiki.puredata.info/en/MediaWiki:Common.css and copy the content to http://wiki.puredata.info/pt/MediaWiki:Common.css