Hey, thanks for your help!
Okay:
1. I've copied the code to my index.php. It's the last thing before </body>
<!-- Piwik -->
<script type="text/javascript">
var pkBaseURL = (("https:" == document.location.protocol) ? "https://www.kenike.fi/piwik/" : "http://www.kenike.fi/piwik/");
document.write(unescape("%3Cscript src='" + pkBaseURL + "piwik.js' type='text/javascript'%3E%3C/script%3E"));
</script><script type="text/javascript">
try {
var piwikTracker = Piwik.getTracker(pkBaseURL + "piwik.php", 1);
piwikTracker.setDoc umentTitle("<?php echo PAGE_TITLE; ?>");
piwikTracker.trackPageView();
piwikTracker.enableLinkTracking();
} catch( err ) {}
</script><noscript><p><img src="http://www.kenike.fi/piwik/piwik.php?idsite=1" style="border:0" alt=""/></p></noscript>
<!-- End Piwik Tag -->
2. Javascript is enabled, other scripts are loaded properly.
3. index.php is placed on my templates/style
Well I noticed that my piwik dashboard default timesetting is yesterday. For today it shows 2 visits and appropriate data. But it dosen't count new visits.
weird...