I was wondering if there was a code where my CSS menu on my HTML website could be repeated without me having to do it on every single page. Is there such a code?
Most designers include those in header files that are referenced on every page. If you are using a CGI (php, perl, python, ruby) then you can make a function like left_menu() and call that to output the menu where needed. Also CGI frameworks like PHP's codeigniter has template systems that make things like that very easy.