Mở Instagram. Chọn Get help signing in (Hỗ trợ đăng nhập). Bấm vào Log In With Facebook (Đăng nhập bằng Facebook). Bấm OK.

Given the above summary, write a detailed text in English for it.
Its a purple-red-orange gradient app with a white, square, camera icon. It's below the blue Login button. You may have to tap Sign in at the bottom of the screen first. It's at the bottom of the page. This method will only work if you've previously linked your Facebook account to your Instagram account. This button will appear below text notifying you that you've already authorized Instagram's use of your profile. After a moment, you'll be taken to your Instagram account within the Instagram app. For Android, tap Continue as [Your Name] instead of OK.