this error occurs when there is output top the page before the header function is called.
according to the error, the output was started around line 9, it's probably on line 8 though:
output started at /home/content/w/d/h/wdhobbs/html/homeschoollife/store.php:9
In most cases, the error is causes by blank space between a closing PHP tag "?>" and the next opening PHP tag "<?php"
it can be a blanks space at the end of the line:
or a blank line between the two:
look at lines 8 and 9 to find the output that is causing the error.