Using template on other files.

I use wordpress for the news on my website but I have other pages for other purposes other than blogging.

I was wondering if there is a way to use your template in other files but by using the codes like <?php get_sidebar(); ?> so that if there’s something in the sidebar i need to change, i don’t have to go through all my hundreds of pages to change it. I can just change it on that one file and it show up on all of them.

I tried the obvious way which was to copy and paste the coding like it was in the wordpress files but that only gave me errors.

I’m slightly new to php and stylesheets… so please tell me in a way I might understand. lol… thanks!