How to Create Publish Post to appear on subdirectories

Hello All,
I am preparing exams preparation website with wordpress.
url: http://www.examsguru.net and I have been trying how I can create sub-directories to take care of some major areas.

I dont want to use subdomains. This is example of what I want http://www.examsguru.net/pastquestions/, http://www.examsguru.net/blog/ http://www.examsguru.net/news/ etc.

I know I can do this by editing the permalinks with specific categories, but I want posts for these /pastquestions/, /blog/, /news/ to appear on their different sub-directories and not from the root folder.

Look at what I tried to do but no headway, I did a fresh WordPress installation on the sub-folder: http://www.examsguru.net/pastquestions/ with the help of simple-script installer and I discovered that its really a fresh installation with fresh login information and fresh customization from scratch – this is really hard to do in all other subfolders I intend to create. Also,I don’t know how to link it to the root domain.