Can't get other pages to show

Hi,
I am using WP again after a long time. I cannot remember what to do to get the pages to show up. The main page shows but when you press a page or category it gives an error that it can’t be found. I know it has something to do with a setting in admin making the links different.
I cannot find the place to set the links and I have searched WP and can’t find the name of it. Please help.

http://www.decentplacetolive.com/
Thanks.