Steam should auto-update your game. If your game does not update automatically:

1. On your keyboard, press the Windows key and type "Steam" in the search bar to locate and open the Steam app.
2. Select Library in the top navigation bar.
3. Look through the list of games on the left side of the screen (or use search) for Halo: The Master Chief Collection, then right-click the title.
4. Select Update.

If you are using the Microsoft Store version on PC:

1. On your keyboard, press the Windows key and type in "Microsoft Store" to locate and open the Microsoft Store app.
2. Log into the Microsoft Store app using the same Microsoft Account you used to purchase your game.
3. In the top-right corner of the Microsoft Store app, click on "..." to the right of your profile avatar.
4. Select Get Updates. The updates for the Xbox Insider Hub app will appear on this screen.
5. On the same "Downloads and Updates" screen, select the Update All button if they do not start downloading automatically.