You forgot "please". D:<
You edit div.box,
example:
div.box {
(left or right): 250px;
}
Naturally you change the number of pixels for where you want it placed. You can also use "top" as an element (like left or right) and move it up and down.
Do you use Firefox? You can get the add on "Firebug" and inspect the element of web pages. Very useful if you want to improve your CSS/HTML writing skillz.