Just use bbcode for your signature. Following below codes:
[img]{location of image}[/img]
replace {location of image} with your image urlOr,
[img]{location of image}[/img]
replace {location of image} with your image url and replace {link url} with your link url
For Example;
[url=http://www.noonhost.com][img]http://www.noonhost.com/support/templates/subSilver/images/logo_phpBB.gif[/img][/url]
will produce this:

Thank Support for this Tutorial.