To get started, set your Steam overlay browser's home page to https://steambookmarks.com/<your_steam_id>

To find your Steam ID, log into Steam via your web browser or the Steam application. From there, click your username in the top-right corner of the window and select Account details from the dropdown menu. Your 17 digit Steam ID will appear near the top of this screen, right below your Steam username.

For example, Robin Walker's Steam Bookmarks URL is https://steambookmarks.com/76561197960435530