A new problem arises

Yesterday, I was somewhat relaxed that my project starts working up to its basic functionality, now just the designing part left, I will work on it and a final product will be in hand, but Alas! 🙁 Today a new problem arose when I refreshed my logged in page, and it automatically logged out instead of staying at the same page and log out only if user want it so. I read about sessions but wasn’t getting why to use session class when we can log in and add post simply. Today I got the role of sessions in a web application. Then I read the complete tutorial of Wt::Auth but it was too confusing, so many classes having different functionality but still linked to each other. Moreover I wasn’t able to find out the code in the example of authentication which should be there to ask user to enter username and password. What to do, not getting any idea.
Secondly, its being too late, I should start preparing for my presentation. It was on ORM (Object relational mapping) but my mentor added a new topic PDO in PHP. God knows what it is, have no idea about anything in php. 🙁