Problem with transfering a WordPress site

I am doing an intership and the owner asked me to transfer one of his sites http://www.vortexsprayonliner.com to a WordPress site. I built this WordPress site http://granitexfloorcoating.com/ for him. It is done. I changed the DNS server and while changing the settings in WordPress to the old URL I set it to the vortexsprayonliner.com URL. This broke the WordPress site I built and now it always forwards to the old site for any updates on settings or pages. Even just trying to log in!!!

I don’t know what I can do. Maybe going into the datase and changing the URL on it but I don’t know which table holds that information.

Can anyone help me?