Website works in Firefox, but not in Internet Explorer

I am trying to help out a friend, i dont know much about websites, but i hope somebody can help me, help my firend. here is his message:
If you use firefox the website comes up ok. If you open it up in explorer its way off center. I want to improve and add to it but its frustrating the hell out of me. www.jacobsenlawn.com is the site
Please PM me or email me at mhoffman@jaysdecalshop.com if you have any suggestions!!
Thanks in Advance!!
Answer #1
Y don’t u jus tell him use firefox
Internet explorer sucks
Answer #2
who wrote the website ?
your bud ?
what’s he use to do his web page editing ?