How do I make this compatible with IE?

I have designed this site http://www.clogs-forwomen.com initially with css3, but it is not compatible with IE, particularly with older browsers.

Could help anyone help correctly code this for me?

Maybe this error is throwing a spanner in the works?

“Fatal error: Call to undefined function nzshpcrt_shopping_basket() in /home/clogsfor/public_html/wp-content/themes/shopme/sidebar.php on line 4”

Sorry forget about this thread, im just going to install another theme.