search engine frendly

I just finished my website and enabled 'search engine friendly urls' and it broke the page layouts eg menus became text lists with no formatting.
Can anyone advise me of a fix please?
www.thelatentimagephotography.com.au

Please enable SEF links with mod_rewrite and rename htaccess.txt to .htaccess in Joomla root folder.

Thanks, that was easily implemented. However, this has effected the lightbox in photogallery plugin. Button "close" and "forward>> <<back" do not display. Also IE doesn't use the lightbox at all. Any clues?

You will have to configure .htaccess not to rewrite image links. Google around to find how to do that

Had a hunt around and endered up back at the htacess file itself which states:

# Uncomment following line if your webserver's URL
# is not directly related to physical file paths.
# Update Your Joomla! Directory (just / for root)

# RewriteBase /

This is so unfamiliar to me. Can you help please?

Unfortunately, I do not know much of configuring .htaccess file .