Open the message, document, or web page that contains the photo you'd like to save on your MacBook. Not all web pages permit images to be saved or downloaded. For example, you can't download pictures from the Instagram website. If the image is in a preview format (e.g., a result on Google), you'll first need to click the image to open it in full-size view. Some images, such as occasional images inserted into articles, serve as links to other pages. If clicking an image opens an unrelated page, click your browser's "Back" button to return to the original image. Your mouse pointer should be sitting on top of the image that you want to save. Hold down the Control key, click the image, and then release the Control key. A pop-up menu should appear on or near the image.  You have to hold down Control for the entire duration of the click, or the menu won't appear. On some MacBooks, you can click and hold the picture to prompt the pop-up window to appear. You can also try "right-clicking" the picture by pressing your Mac's trackpad button with two fingers, or by pressing the right side of the trackpad button on some MacBooks. It's in the context menu. This will prompt the photo to download immediately into your Mac's "Downloads" folder, which is usually a folder literally named "Downloads".  If you're using a browser other than Safari, you can click Save Image As instead. This option will allow you to select a name and a specific download location for the file before you download it. You can open the "Downloads" folder by opening Finder (the blue, face-shaped app icon) and then clicking Downloads on the left side of the window. If you set your Mac's default "Downloads" folder to a different folder (e.g., the "Desktop" folder), you'll find the image there instead.

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Write a summary of the previous text in Vietnamese:
Truy cập ảnh mà bạn muốn lưu. Mở ảnh nếu cần. Đặt con trỏ chuột của máy Mac lên ảnh. Mở trình đơn chuột phải. Nhấp vào Save Image to "Downloads" (Lưu ảnh vào "Downloads") trong trình đơn đang hiển thị.