Recommended tutorials

Problem!
I was also running a tutorial from CodIgniter:
https://ellislab.com/codeIgniter/user-gu...pages.html

When I try to access home or about pages, I get an error:
"No input file specified."

Why do I get this error and how do I resolve it please?

CodeIgniter is installed in sub-directory of my existing site.

Thanks!

Why are you posting this twice?
http://forum.codeigniter.com/thread-775.html
Not appropriate!

Your forum's code has a UI/UX bug: When I tried to create a new thread I got a confirmation page with some messages on it. However it was up for only 2 seconds and I did not have a chance to read what it says! Then I got redirected somewhere else. I checked the forum and realized that the thread was not published. I thought that something went wrong but I did not know what, and therefore I posted it here because the topic of this thread is related to my issue! Please bring it to the attention of your programmers. Thanks!