Hi Ivee,
Unfortunately, I could not access your website for some reason. Would you please kindly double-check? And also, make sure that there is no Firewall on your hosting service as it might have country IP restrictions and we are from various parts of the world.
I think the correct course of action is to set the Page Template to Blank - No Container | Header, Footer so you will have no container on the page and also have access to header and footer. Kindly click here for more information on how to set the Page Templates.
Then please use Cornerstone to add sections. Whenever you add a section, please go to the Row settings and turn off the Global Container option:
So, whenever you want to have a full-width section, turn the option off. FOr the other sections that need the Global Container kindly keep the option turned on.
Here is an overview of layout creation using Cornerstone, and here is detailed information about Rows.
Thank you.