Find the location that you are interested in in, either the Global Map or the Global Area Grid. Set your cursor over that location until its Twiki name pops up. Click on this pop up and one of two things will happen.
A location page appears with other entries on it, or
A menu appears with an admonition that this page is yet to be created.
Right now most locations are of the second type where no page has yet been created. To create the page go down to the third option on the menu "If you would like to create this page:" and click on the link to create the page.
Now that you have created a page, options 1 & 2 above have come together and you can enter data on the location page. (For instructions on how to add data to a page see AddingData.)