The tab that you linked to is a custom Facebook application developed specifically for Coca-Cola. You can learn how to create your own Facebook application here (see the Profile Tabs section), but there are several existing applications that you can use if you don't need anything very special. For example the Static FBML application allows you to create a tab on your Page with static content.
The maximum width of a Page tab is 520 pixels.
After creating the tab, go to Edit Page and then Manage Permissions and change the Default Landing Tab to the new tab. This only affects visitors who have not Liked the page. Admins and anyone who has Liked the page will always see the Wall by default. This option is not available for some Pages, including Community Pages, Places, and Pages that have been merged with a Place.