Hey, I know about the icon, title of the Window, and text of the text box:
1. You just browse to the SFX (*.exe) you have created in WinRAR....
2. Right Click On It....->Show Information...->Click On SFX Tab
3. Here you click on Advanced SFX Options
4. Now u can see, u can do a host of things, which includes, Title of the Window, Icon, Text, Licence, Path To Extract, etc.
As for changing the image to the left, Do what Nikhil has said.....