WordPress installation just doesent work :(

Are you trying to start over using WordPress from scratch, or are you trying to repair/restore the installation that you previously had?

Seems as if you have not installed properly recheck all files and folders using ftp or replace all files and folders from fresh download.

I might agree with Andrew above, ensure your URL is correct. However in your post above you said..

“And when I put in the username and password(the same ones that I used while changing wp-config.php) then it gets me back to the same page as I was at.”

This sounds incorrect. The settings in your wp-config.php file are for your database not for your WordPress admin.

Check this by logging into your database via PHPmyAdmin with those login credentials.

Once in the database you can reset the admin password and username so you can log back into WordPress – http://codex.wordpress.org/Resetting_Your_Password

and then go to the options table and check the site url and blog url settings as this might be incorrect as mentioned by Andrew. http://codex.wordpress.org/Changing_The_Site_URL

That article above has all the info on the database stuff. If you still have an issue let me know. WordPress really is easy to use and this must be a simple error or misunderstanding somewhere. Cheers my friend 🙂