[Serna] PDF Generation Help

Hi,

I'm new to DITA and serna. I've downloaded a trial version and created a small 
dita test document from which I wanted to generate a pdf. All of this worked 
wonderfully, however I want to add my own header and footer to the generated 
pdf and cannot find out how to achieve this. I've looked in many forums, faqs 
and tutorials, but without avail. Maybe someone on this list can give me hint, 
how I can achieve this. Thanks!