Arc Help

Use Help in the menu bar: Getting Started, Essential Keyboard Shortcuts, and Help Center (for more). Pin tabs to save for later so you can keep things you need within reach (like a bookmark bar). Use spaces for work, life, hobbies, efforts (or projects), etc. 

Watch the Arc videos that cover all the key features and show how to use Arc, along with other interesting stuff like demos of their Windows version, progress on their effort to bring Swift to Windows, etc.

View their Release Notes every Thursday when they update the Arc browser with new features, provide tips and techniques, and address any bugs, performance, or perform other tweaks to improve the product.

Articles

Release Notes are always available as text, but sometimes they might be on a Easel or in a YouTube video.

These provide some more background about the company.