I'd avoid using htauth as your username and password are generally transmitted in clear text. Therefore it really isn't secure.

Better is to have them connect to an encrypted form (using SSL) and submit their login info. Have the script verify the user and set a session cookie.

They told me to create a location configuration directive on httpd.conf which i did but remove the Require user Nik which i did

If you really want it limited to the user Nik (which I assume you do judging from the code you provided) and you want to use the htauth method, then their advice was wrong. You need to require user Nik or require valid user.