[Theme: Thematic] Moving search form in header

I would like to move the Search form from Primary Aside inside the Header (at the right).
I’m using a child theme and testing il through Xampp so cannot include link. Which files have I to modify, I tried with header.php and this code:

<form method="get" id="searchform" action="http://localhost/creus">
			<input class="field" name="s" id="s" placeholder="Search" type="text">
			<input class="submit" name="submit" id="searchsubmit" value="Search" type="submit">
	</form>

but it lays to the top/left and cannot move it with CSS. I want it just like in the ThemeShaper/ and possibly with the same layout!
Thank you very much in advance.
Bruno, Schio, Italy