The Addons Menu is located in the Main Menu, and it is used for manipulating addons, allowing the user to enable, disable, subscribe and unsubscribe from addons.
View the addons you are subscribed to, quickly enable or disable all subscriptions. In the list of subscriptions which appears on the right, you can disable/enable and unsubscribe specific addons.
When an addon is disabled, it means it is not loaded in the game, but will still be updated when the author makes any changes. When the addon is unsubscribed, it will be removed from the game and will not be available for use, unless you decide to subscribe to the addon again.
2. Viewing addons
Using the set of buttons, you can quickly view addons by categories: Gamemodes, Maps, Weapons, Tools, NPCs and Vehicles.
3. Friends Uploads
Using the buttons you can view the addons which your friends have uploaded.
4. My Uploads
View the addons which yourself has uploaded.
5. Open Workshop
Selecting this option will allow you to open up the Garry's Mod Workshop in the steam browser, the advantage of this is that it offers you with a few search options.