kylesforza on "Error when uploading a theme"

This is the error I'm getting when I try to upload a theme

Warning: POST Content-Length of 21662666 bytes exceeds the limit of 8388608 bytes in Unknown on line 0

I'm running the Wordpress installation in XAMPP. I tried to search but they all suggest to update php.ini file. Where do I find this php.ini file? o.O