Your files need to go into the public_html directory.
If by web root, you mean the www directory, you can also put them in there since all the www directory does is serve as an alias for public_html.
However, if you mean /home/prk770 (assuming that is your cpanel username) putting the files in that folder will not work.
Regarding what directories do what, i'm not 100% certain of everything, but I am pretty sure on the following things:
public_html is the web root directory as the webserver see's things. When you enter your domain into a browser, this is where the server looks for your files.
www is an alias that points to the public_html directory
public_ftp is used if anonymous ftp is enabled on your account. Any time someone connects anonymously to your account (if that option is enabled in cpanel), any files they upload will be put in this directory.
There are other directories, but they are system directories used by the server for various things (access logs for example)
There are also several files in the root directory (the home/username directory) used for things like access control (.htaccess), fantastico script installs (now obsolete), and softaculous script installs.