Very simple - put an <a href="/home">Company name</a>
inside your H1 element, and apply your image replacement styles to h1#logo a
(or whatever selector you use). You'll need to add display:block;
to the styles, to have the anchor behave correctly.
Let me know if you need more detail than this!
Extra detail:
OK - I usually use the following HTML and CSS for image replacement:
HTML:
<h1 id="logo">
<a href="/home" title="Back to the home page">[Company name]</a>
</h1>
CSS
#logo a {
display:block;
width: 200px; /* Or whatever you like */
height: 0;
padding-top: 100px; /* The required height */
text-indent: -999em; /* negative text indent, leaves the box alone, and in ems to scale with text */
overflow: hidden;
background: /*whatever you like */;
}
This is a kind of 'double-strength' - the height:0/padding-top technique creates a box the size you need, but without any room for text to display (the background image will appear in the top padding, but the text won't). The big negative-text-indent is just a safety for browsers that get things wrong occasionally (old webkit used to have problems - not much of an issue nowadays).
Let me know how you go!