How do I change header image

Hi, I am new to this so I may be overlooking something really obvious... Anyway, how do I change the header image (the text Hot Leafs, environment friendly Joomla! design and the image at the top right) to something of my own choice?

Thanks for helping me out.

create your own logo image (415x116px) and re-place old one in:
templates/hot_leafs/images/logo.png

How can I change the size if I want to use a logo that is larger? I tried editing the css to no avail.

Open index.php of template and change width and height attributes of logo image html tag:

<img src="<?php echo $template_path ?>/images/logo.png" width="415" height="116" alt="green joomla template" />

also you may need also to change in layout.css:

.logo {
height: 116px;
width: 415px;
float: left;
}