To send an email, you open your email account and click a 'New Email' or 'Compose' button. Then you type the recipient's email address in the 'To' field, write a subject line that describes your message, and type your message in the body. Finally, you click 'Send' to deliver it.
Have children write a simple email to a trusted adult or themselves. They type an email address, write a subject, and compose a message. Then practice clicking Send.
An email is a digital letter, and its structure mirrors the parts of a traditional letter — recipient, subject, and body — plus a few technical fields unique to digital communication. You already know how to read emails from your prerequisite work, so you've seen all the parts; now you're filling them in yourself. The biggest shift from reading to writing is that you're now responsible for two things the reader doesn't see in a received email: choosing the right address and writing a subject line that tells the recipient what to expect before they open it.
The To field is where you type the recipient's email address — a unique identifier like a phone number, except that even a single wrong character sends your message to a stranger or nowhere at all. Most email apps will suggest addresses from your contacts as you type, which helps avoid errors. If you're sending to more than one person, the CC field (carbon copy) is for people who should receive the message as a courtesy but don't need to act on it. The BCC field (blind carbon copy) sends the message to someone without other recipients knowing — useful for forwarding a conversation privately.
The subject line is the headline: it tells the recipient what the email is about before they click. A good subject line is specific enough to be useful ("Question about Tuesday's meeting" is better than "Question" or leaving it blank). When you're first learning, erring toward more detail in the subject is better than less — blank subjects look like spam, and vague ones make people delay reading. The body is where you write the actual message. Keep it clear and complete: state what you need, provide any necessary context, and end with any action you want the recipient to take.
When you click Send, the message is transmitted immediately to the recipient's inbox — there is no unsend option in most email systems once it's gone. This is why it's worth a quick review: check the To field (did you type the right address?), the subject (is it clear?), and the body (is it complete and clear?). Reading your own message once before sending, the same way you'd check your backpack before leaving school, catches most mistakes before they reach someone else's inbox.