Click the Extension Manager icon. on extreme right. Enlargement of Extension Manager icon. or
Select File, then Extension Manager
The Brackets Extension Manager Window opens
Extension Manager Top Menu.
Available: Lists all available Extensions
Jon's Tip: For more information on an extension Click More Info... which is supplied by Github. Further information can sometimes be found by a Google search.
To Install. Click the install button
Themes: Lists Color Themes for The Brackets Editor.
Installed: Lists all the Extensions you have Installed.
This is where you can easily Disable or Remove Extensions you do not want via the Disable or Remove buttons.
Downloads: Lists all the Extensions available in order of popularity. Last updated: Lists all the Extensions available in order of update date. Latest updates on top.
Default: Lists all Extensions that are already installed by default.
Search: Narrow the selection with searches such as HTML5, Bootstrap, Bootstrap4, JQuery, etc.
Normally the icon is gray. If it is green there is an Update for an installed extension available.