How can I make a clickable header on Tumblr (with several links to click)

[Fisken]

I would like to make a clickable header with several links to click, for example the possibility to click Facebook & Twitter icons to get redirected to my twitter and Facebook page.

I know how to make the clickable image and get the html for it. But where in the HTML on tumblr should I insert it? Can I override the custom header with my HTML header somehow?

Appreciate all the help I can get,

Thanks.