Well first of all you don't want to redirect the user to separate landing pages, you want to customize the landing page to the person who logged in. The idea is that if user A logs in, the page they see next is the same page everyone gets, but the PHP code on that page renders all information and graphics specific to user A. If user B logs in, again they are taken to the same page but that page pulls all the data out of MySQL and customizes the page according to user B preferences.
In this situation the landing page is called a "view" into the data from MySQL (the model). The PHP code acts as the "controller" here determining what rules apply to the user logging in and what views to show them. This is the process behind the MVC (model-view-controller) design pattern.
The reason I am bringing this up is because 1) You don't want to have to create several pages for each user. 2) You want to code only one page for easy maintenance later and keep rules in one central location and 3) allows your site to extend easily without any work.
But if you INSIST on redirecting users to other pages, all you need to do is check the login is successful and issue the appropriate redirection using the header() function. But remember that header() cannot be used on any pages where content has already been sent or displayed to the user PRIOR to using the function. So that means no echo / print statements or displaying HTML output before using header(). Otherwise you are going to get a "headers already sent" error.
Good luck.