page's width

i'm trying to make a webpage for a company and they need that the page has 100% width.

(i'm sorry for my english), i'm trying to say thath when i make a page, all the element are in px not in %. and when i open the page in another pc thath has a bigger screen, the index look smaller, and i can see the information thath i want to show only scrolling the page.

someone can help me ? pleaseeeee!