Isn’t it already at the top of the page? That’s what a header is. Can you be more specific. Are you talking about moving the title up higher in the “box” that is at the top of the page in the section called “header”?
Kubrick’s theme (default) does some funky things so the fix is two fold. The section you are looking at called the “header” is:
<div id="header">
<div id="headerimg">
<h1>Title Name
So there are three things that control the look of the header. The “header”, “the headerimg” which controls the image as well as the layout of stuff inside of that section, and “H1” which is the heading and the specific “title” of your site.
The CSS (style) for this section is controlled in two sections. One is on the index.php (or header.php) itself and the other is in the style.css file. The author separated this so people could more easily change the header look, but it does make things a little complicated for providing support.
Play around with the margins and padding in the following selectors (names) in the two places to move it to where you want. Experiment. Maybe you like it over to the left margin (text-align:left) instead of centered. Maybe you want it red instead of white. Or larger. Play with it. It’s pretty easy to figure out that margin-top:100px is a HUGE margin from the top.
#header {attributes here}
#headerimg {attributes here}
#header H1 {attributes here}
or
h1 {attributes here}