1. You can copy files to your account using the ftp. You may use your cPanel username and password for this. You can use different FTP clients like CuteFTP, WS_FTP or SmartFTP for uploading the contents.
2. You can also upload files through cPanel File Manager. Your cPanel is located at http://domain.com:2082
and you can login by using the username/password .After reaching the File Manager,browse to public_html folder and use the feature "Upload file(s)".
3. All files that you need to access via http (web browser) should be placed in /home/username/public_html/ directory.
4. Both /home/username /www/ and /home/username /public_html/ ends up to the same location so you can use the either one.
5. You may upload the main page such as index.html or index.php to the public_html/ directory in order to make it your main page.
6. You may put the pages in the same directory public_html/ directory or can make separate directory for it and make a link it from your index page.
I hope this information helps.