You are allowed to edit pages if you become a member of this site. To join, please go to the page for Joining This Site.
If you are a member, simply click on the edit button at the bottom of any page. This will open an editor with a toolbar pallette with options.
To create a new page, use the white box in the blue left column below, insert what you want the page to be named, then edit it!
If you want to use the same functions you see on other pages for your own page, then click on edit to read what happens inside the pallette - you can copy and paste into your new page and modify the text. Please be careful, though, to leave the work of others intact unless you are making corrections or appropriate updates.
Although creating and editing pages is easy, there are a lot more options that allows creating powerful sites. Please visit Documentation pages to learn more.