The problem I have is that your CSS is modified, so if I use my test blog with the stock Wu Wei theme, what I'm giving you can only be used as a guide.
1. Insert an image left-aligned at the very beginning of the page or post (220px max width).
2. Switch to the HTML tab and add the margin-left and margin-top inline CSS to the image code (you will have to adjust the numbers to get it to work with your customized theme).
You can see an example here: http://allthekingshorses.wordpress.com/
Do remember that in doing it this way, if you ever change to a different theme, you will have to edit things, and if it is a more standard designed theme (title above post/page content) you will have to edit each page and post to get rid of the inline CSS that moved the image over in Wu Wei