Build some notification system on website

First you need to know Joomla | Ajax | Php | Java .... Details First i need to build on user panel a specific form where registered users can select categories who are interested. When somebody post something in a specific category or categoryes that user who have that category(es) on interest will get a pop-up on left or right side (like freelancer.com have) to inform a user when a item is posted - you can see it in [login to view URL] For this i will need the menu button with all logs of notifications (like freelancer have). - you can see it in [login to view URL] Pop-up must appear only on desktop For mobile i will ned just the menu button with logs. - you can see it in [login to view URL] The webiste will be on Joomla , i want the notification system only !!! Further information you will receive