Simple search in the header or footer

Hi, I install the simlesearch package https://www.neos.io/download-and-extend/packages/flowpack/flowpack-simplesearch.html

It works. Now I found in the backend the search content element. But how can I add the search field to the sharedheader or footer on the page? Can you help me?

Just build a form as the content element does. It has no hidden magic. If you manage to create a form with the same name and action you should be good to go.