Double-click the Photoshop app icon, which resembles a blue icon with the letters "Ps," then click on File in the menu bar at the top of the screen and perform one of the following actions:  Click Open... and then double-click a project to open an existing document. Click New... to create a new document, then add any images that you want to use. You can do this by clicking the Select menu item at the top of the window and then clicking Deselect in the drop-down menu. In the "Layers" section of the Photoshop window, click the layer that you want to mask. Depending on the level of detail that you want to preserve, you'll have to use one of the following tools for this step:   Marquee Tool - Used to select a large area without worrying about fine edges. Click the dotted-line icon near the top of the "Tool" section, then click and drag your mouse around the area that you want to show or hide.  Pen Tool - Used to select fine details. Click the fountain pen-shaped icon in the "Tool" section, then click and drag your mouse around the area that you want to show or hide. It's at the top of the window. Doing so prompts a drop-down menu. On a Mac, this option is at the top of the screen. You'll find this option in the drop-down menu. Doing so prompts a pop-out menu to appear. Choosing the Reveal Selection option will cause only the selected area to display while the rest of the layer is masked, while choosing Hide Selection will mask the selected area of the layer while preserving the unselected portion. If you want to move the mask up to display above a different layer, click and drag the masked layer in the "Layers" section up or down until it's positioned where you want it. Click File in the upper-left corner, then click Save in the drop-down menu. If you created a new project, doing this will open the "Save As" window in which you'll need to enter a file name, select a location, and click Save again.

How would you rephrase that briefly using Vietnamese?
Mở hoặc tạo tập tin Photoshop. Bạn cần chắc chắn rằng mình chưa chọn mẩu ảnh nào. Chọn lớp. Chọn phần mà bạn muốn ẩn hoặc hiển thị. Nhấp vào mục trình đơn Layer đầu cửa sổ. Chọn Layer Mask từ trong trình đơn thả xuống. Nhấp vào tùy chọn Reveal Selection (Để lộ vùng chọn) hoặc Hide Selection (Ẩn vùng chọn). Di chuyển mặt nạ nếu cần thiết. Lưu lại thay đổi của dự án.