CMS for existing Newsfeed of our Website

We have on an existing .php website a newsfeed that gets new input by writing code in the php file. This newsfeed should get a cms backend where our marketing agecy can simply add new posts. The site structure now looks like that: /page/[login to view URL] /page/[login to view URL] /page/[login to view URL] each site has three posts with a short info of the post and also a preview of a picture. If user clicks on the post he gets a new site with the full post and also a little gallery of added photos (if needed) code for used gallery on our website is already existing. If new contend is added, post will get on the first page of [login to view URL] and all older posts get one step down in the list. If necessery a new page ([login to view URL]) will be createt. And so on. All Posts get catergories (news, info to a appontment,....) User can sort entries by the category. We need three users in the cms for ading new posts. Project max is by 200€ please just bid if you can make it in this budget!!