That you will edit on each page. The content can be copied and pasted right from the old site if you like. It is in the old table style, but it really doesn't matter how you do it. You can recreate it all without tables if you want to take the time. Basically you could just use this page as a template for all of the others.
The menu navigation above is dynamically loaded from the file in the "includes" folder then "nav.php" file. The footer below has very little on it currently... but it too is dynamically loaded from the "includes" folder then "footer.php" file. To make changes to these php includes you just need to have any of this sites new pages open and then select either the nav or footer pages pictured below:
One possible issue with php is that when you test it locally on your computer... the PHP portions will not display. (You just wont see the navigation or the footer info, not a huge deal). Your computer needs to be running a server that can load it if you need to see it. (I use WAMP server at from http://www.wampserver.com/en/. If you don't want to complicate things by running a server, you just upload your pages and test them online.
I won't go into the navigation too much because basically you can just copy and edit what is already there. It is a set of unordered lists <UL> and list items <LI>. You really don't need to understand them to use them. Replace the placeholder "#" with whatever page you want to link to.
To make things work correctly you will need to upload some folders to your server. The folders... css, js, and includes will need to be on the root level. Then just upload your new pages on the root level as well... just like they are now. You will need to make sure that the pages are not .htm or .html... rather they need to be .php. (index.php, history.php, members.php... etc).
If you don't like things like font, font size, or color... these things can be edited in the styles.css page. (Found on the same line as the nav.php and footer.php pages) I don't know if you understand how to use .css files (Cascading Style Sheets), but give it a change before you go back to tables. Every time you edit a font or font color with tables you have to declare the values for each section. This is WILDLY time consuming and very frustrating. With .css files you declare a style to an element such as all paragraphs, (<p> Some Text </p>), and then to change all of the paragraph colors you just edit the .css file.