Internal Webpage

I need a website that will allow people to create a user name and then, me as an administrator of the site, will grant a username and password. All the content on it must me editable for the administrator of the site from a friendly CMS. Me, as an administrator, will also grant different levels to the usernames. In other words, I will choose what they will see and what they won't. All the site can be build up with a Wordpress template - I had a site like this one before and it was entirely built up with templates.- Once I sent them their Username/Passowrd and they've logged in; they will see a menu in the upper part of the site. This menu must be editable to the administrator of the site. In other words, from a CMS; if I want to add more or delete options; I must be able to do it. The "Home page" will have a small paragraph for the latest news. It might contain images, so the space for them must be considered. Since the News will going to be updated on its regular basis; the user must be able to see the previous news if the click on the button that reads "Previous News". Below, you will find the Social Media Icons linking to our social media accounts (Background color must be different in order to make a distinction). On the very bottom, a Legal Disclaimer will be posted. Each Option on the Main Menu Bar will have a dropdown menu. This menu, as all the site must be easy to edit from a CMS of you're administrator of the site. All this site will contain Documents that I constantly have to send to a lot of people; the general idea is for them to log in and download them without contacting me; but I have to control the access and profiles. Once you clicked an option of a dropdown menu, you will have a brief introduction (only text) and a list of the documents with a thumbnail of the file. At the extreme right of the site, an index menu will be shown. If I click any of those options; I will be taken exactly to the position where that file is. Me, as an administrator, will also need an option to see who downloaded what, when and how many times. So, if "Username1" clicked "FileX" 5 times, I must be able to know it and know when they do it. The adminsitrator of the site will control the profiles and will also delete usernames anytime he wants.