The URL somehow got messed up when you inserted it. Please edit your style.css and make the URL look like the above without doing a copy/paste.
Also, the size of the image is 950 x 170. That will not look right unless you increase the height of the header area.
You also need to hide the text site title and description.
You do all of that by adding this to the end of style.css:
body.header-fixed div#header {
background-image: url("http://www.soulpoweredcoaching.com/wp-content/uploads/2012/01/header.png");
}
body.custom div#header {
height: 155px;
}
body.custom div.header-link-text {
display: none;
}
h1#tagline {
display: none;
}
Note that I have included the header image in this code. You do not need it twice, I just put it here for completeness.