Basic web application in php: Cloning functions of another site

I already have the front-end of my website setup here: [login to view URL] My site is already running Wordpress, which you can do your development on. Or you can use another other framework if you want. This project is to develop the "back-end" of the website, which is basically cloning the functionality of [login to view URL]\_REMOVE\[login to view URL] (not the front-end website, the members-only section of their website). There are about 10-15 different pages in involved, most of which are pretty basic. I would like the design to fit in with my existing look of [login to view URL], and also using design inspiration from [login to view URL] (log into their members-only section). Please see the attached document for more details.