Hi, welcome to the forums.
You can put an image in your blog and it shouldn't be "out of your league"
A link to your blog would be helpful as would the name of the skin your using.

Sorry. the link is www.joycemoorebooks.com/blog.htm and the skin is evocamp (I think). My web designer set things up and left it for me to do and I don't have a clue and have been reading all night trying to see how to make it look decent. Thanks for any help.

In the style.css file for that skin you will see

#header {
color: #FAF7E8;
width:960px;
clear: both;
padding: 0;
margin: 0 auto;
height:160px;
background: #330000 url(img/zekehead.jpg) top center no-repeat;
}

you can replace zekehead.jpg with your own image.
You may have to also edit the height etc depending on your image.
Cheers

Thanks so much! I'll see if I can handle that :p