Familiarize myself with WebExt-structure

[engeld]

• Familiarizing with the WebExtension format and structure, and build a basic example.
• If your extension is based on XUL and XPCOM, whether it's an overlay extension or a bootstrapped extension, see Comparison with XUL/XPCOM extensions to find out how WebExtensions can correspond with the legacy APIs you're using.
• If your extension is based on the Add-on SDK, see Comparison with the Add-on SDK to find out how WebExtensions can correspond with the legacy SDK APIs you're using.

https://developer.mozilla.org/en-US/Add-ons/WebExtensions/Porting_a_legacy_Firefox_add-on