PHP Login isn't working

I'm working on this site
http://preview.tinyurl.com/66hv3o

and when you login I want it to be able to talk to you to the user panel.

Only problem is I want the users to be able to login on the front page (look into the top right corner)

But whenever I type in the username and password, I get taken to the default login page and not the user panel home page.
http://preview.tinyurl.com/5thlxf

You can test the login with the following credentials:

user: test@nupixel.com
pass: testtest

Any suggestions? Did I make my error clear?