Mở Facebook. Đi đến ảnh mà bạn muốn tải xuống. Nhấp vào ảnh. Chọn ảnh. Nhấp vào Options (Tùy chọn). Nhấp vào Download (Tải xuống).

Given the above summary, write a detailed text in English for it.
Go to https://www.facebook.com/ in your browser. This will open the News Feed if you're logged into your Facebook account. If you aren't logged into your Facebook account, enter your email address (or phone number) and password in the upper-right side of the page to log in. Scroll through your News Feed until you find the photo that you want to download, or go to the profile of the person who posted the photo to find it.  You cannot save cover photos on Facebook. You can go to a person's profile by clicking the search bar at the top of the Facebook page, typing in the person's name, clicking their name in the drop-down menu, and clicking their profile in the results. This will open the picture in full-screen mode. Place your cursor over the picture to do so. You should see several different options appear around the perimeter of the picture. Your mouse cursor must be on the picture itself before you can proceed. As long as your mouse cursor is on the picture, this option will appear in the bottom-right corner of the picture. Clicking it prompts a menu to pop up. This option is near the top of the pop-up menu. Doing so will prompt the picture to download onto your computer.  For some browsers, you'll first have to select a save location and then click OK. Your browser's default download location is the Downloads folder.