On what? Xanga or createblog?
xanga:
CODE
<!-- begin code provided by createblog.com -->
<a href="SITE LINK" target="_blank"><img
src="IMG LINK" border="0px"/></a>
<!-- end code provided by createblog.com -->
createblog:
CODE
<!-- begin code provided by createblog.com -->
[URL=SITE URL][IMG]IMG URL[/IMG][/URL]
<!-- end code provided by createblog.com -->