Shopify | non-embedded app | Reroute traffic to my independent web portal

[cthumau]

I intend to create a standalone (non-embedded) Shopify app. When someone installs the app, I want to provide them the option to click the "Open" button to access my admin area.

1. How can I add a button that says "Open"?
2. How do I reroute traffic to my independent web portal?