How to show bookmarks only on new tab in Firefox?

1. Make sure Menu Bar is enabled.

https://infallibletipsandtricks.blogspot.com/2021/02/menu-bar-mozilla-firefox.html

2. Go to View –> Toolbars –> Bookmarks Toolbar. 

3. Select Only show on New Tab.

Menu Bar Mozilla Firefox

 1. Right click near the Tab.

2. Select Menu Bar.

How to Capture traffic in Fiddler?

1. Fiddler can be downloaded using the below link.
https://www.telerik.com/download/fiddler

2. Select Capture Traffic under File menu.