The headers already sent error means that there is output to the page before the header() function or session_start() function is used.
If you exmine the error message closely, the section in pereenthises:
output started at C:\xampp\htdocs\graceAndLace\homeGraceStore.php:83
tells you where to look for the output that is causing the problem.
look around line 83 of the homeGraceStore.php page.
Usually the problem will on the line before the error is reporting. In most cases the problem is caused by a blank line between a closing php and opening php tag:
in some cases, it can be caused by a blank space after the closing php tag:
it can also be caused by an html comment between the tags, or a misplaced echo statement.
If you cannot find the cause of the problem, please send a copy of your page in zip archive so i can inspect the code.