Mở Contacts (Danh bạ) trên Android. Nhấn vào biểu tượng new contact (liên hệ mới). Chọn vị trí lưu trữ. Nhập tên người liên lạc. Nhập số điện thoại quốc tế. Nhấn Done (Hoàn tất).

Given the above summary, write a detailed text in English for it.
It’s usually a blue icon with a white outline of a person’s head. You’ll find it in the app drawer. It’s at the bottom-right corner of the screen. Look for a gray silhouette of a person’s head with a plus (+) symbol. This is where WhatsApp will save your new contact. You can choose to save it to your device’s internal storage or your SIM card.  Start by typing the “+” symbol, followed by the country code (e.g. 44 for UK). For example, a UK phone number would look something like this: +447981555555. It’s at the top-left corner of the screen. Your contact is now added to your Android’s phone book, which means you can now chat with them in WhatsApp.