Keep getting "403 Forbidden" in Localhost

[enchance]

I just installed apache, php, etc. But how come when I try to open a file in localhost I get the ff message in my browser in html
Forbidden
You don't have permission to access /agi/ on this server.
How can I view my files if ubuntu won't let me? My folder is in /var/www/

[twistedtwig]

what is the URL you are trying to view? where exactly (fully path) is the file held?

What are the permissions of that folder and file (ls -l)