changing header

Hallo!
I have this wp theme and I would like to replace the header with my own logo!
That’s what I tried…but I didn’t succeed!

header.php:

I put this:

<div id=”header_logo”>
<img src=”<?php bloginfo(‘template_directory’); ?>images/dgclick.jpg” alt=”<?php bloginfo(‘name’); ?>” />

and deletet that:

<div id=”header_logo”>
<h1 class=”blogtitle”>/” title=”<?php bloginfo(‘name’); ?>”><?php bloginfo(‘name’); ?></h1>
<div class=”description”><?php bloginfo(‘description’); ?></div>
</div>

somehow it only shows the alt text…so no logo ??

then I tried to change the css…

#header_logo {
float: left;
padding: 30px 30px 10px 30px;
background: url(logo/dgclick.jpg) no-repeat;

}
but it didn’t change anything…
please help me!

thanks
zucchini