Do not panic if we receive something like this header error.

Warning: Cannot modify header information - headers already sent by (output started.. at /home/hewwitea/public_html/includes/theme.inc:953) in /home/hewwitea/public_html/includes/common.inc on line 99.

Go to your cPanel at 'http://www.my_domain.com/cpanel

Login username and password

Select File Manager > public_html > includes > {click on right filename] theme.inc > [right-hand box opens] Edit File > [new window opens] > [scroll down to END page] > [cursor immediately after last character] > Delete [x times, to bring up last line in page] > Save

Note: This is file MUST END at last character precisely. No empty lines underneath.