Page Layout Templates are important to create organize your Sites Pages Quickly. you can also Apply a Template to any Page at Anytime.
Template Tips: You need to be careful not to overwrite the original content of the Page - or, If necessary, copy the content out of the page and then apply template and paste the content back in.
Create a Page Template:
Flash Video Tutorial: How to Create a Page Template
Flash Video Tutorial: How to Create Pages from a Template