How to upload html file to root directory of shopify

Hey mate.

Apologies, i’m probably not using the right terminology. This is my first time setting up an online store.

FB wants me to set up a specific code on my website (options are via DNS, meta-tag or HTML) so that it can verify that the ads that i run on FB are sending people to the right website. I think i only need to do it via one of those three methods, however apparently DNS and meta take up to 72 hours to be read by FB. So i’m trying to figure out how to do it with HTML (or liquid) so that it’s instant. I’ve downloaded my specific HTML file but the instructions say to copy it to the root file of my website. Which is where i’m stuck…

Hope that clarifies my question.

Mitch