image too small on header

Hello. I have downloaded and installed The WordPress Magazine theme by gabfire
and i’m confused about the header image. I want to put some little image but its TOO little. So, i wanted to know how can i change the header to put a largest image.
The screenshot are here.
See it, and you will understand what i mean.
I don’t want so tiny image, just more bigger but not too much.
When i change the title font size, the header changes, and i can see the image in the way i wanted, but the title is too big now.
Thank you in advance for reply.
Regards

THis is a part of the CSS
body {
background:#666;
font: 1em/1.5em Verdana, Geneva, Arial, Helvetica, sans-serif;
}

h1 {
font:3em Georgia,Times New Roman,Trebuchet;
margin-bottom:10px;
padding-left:45px;
background:url(images/flordeju.gif) no-repeat left center;
}

h1 a:link,h1 a:visited,h1 a:hover {color:#444;}
h2 {
font:bold 1.2em Georgia,Times New Roman,Trebuchet;
color:#222;
padding-bottom:3px;
border-bottom:1px solid #efefef;