Tap the Gmail app icon, which resembles a red "M" on a white background. This will open your Gmail inbox if you're logged in. If you aren't logged in, select your account and/or enter your email address and password to log in. It's in the bottom-right corner of the screen. Doing so brings up a new message window. Tap the "To" text box, then type in the email address of the person to whom you want to send an email. If you want to CC or BCC anyone on the email, tap on the far-right side of the "To" text box, tap either Cc or Bcc, and type in the email address you want to use. Tap the "Subject" text box, then enter the subject you want to use. Generally, a subject summarizes the email in a few words. Tap the "Compose email" text box, then type in whatever you want to use for your email. If you want to place a file or photo in your email, do the following:  Tap at the top of the screen. Tap Camera roll (iPhone) or Attach file (Android). Select the photo or file you want to use. It's a paper plane-shaped icon in the top-right corner of the screen. Your email will be sent.

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Write a summary of the previous text in Vietnamese:
Mở Gmail. Nhấn vào biểu tượng "Compose" ở góc dưới bên phải màn hình. Nhập địa chỉ email. Nhập chủ đề. Nhập nội dung email. Thêm tập tin hoặc ảnh nếu cần thiết. Nhấn vào nút "Send" với biểu tượng máy bay giấy ở góc trên bên phải màn hình.