There are two common ways the question "how to send mail" can be interpreted: sending traditional physical mail (postal letters) and sending email (electronic mail). Here is a concise guide on both:

Sending Physical Mail (Postal Letter)

1. Write your letter and put it in an envelope.
2. Write the recipient's address in the middle on the front of the envelope.
3. Write your return address (sender's address) in the top left corner.
4. Affix the correct postage stamp in the top right corner of the envelope.
5. Drop the letter in a mailbox, blue collection box, or bring it to a post office for sending.
6. Your letter will be sorted and delivered to the recipient's address by the postal service.

Sending Email

1. Open your email program or service (like Gmail, Outlook, Apple Mail).
2. Click the "Compose" or "New Email" button.
3. Enter the recipient's email address in the "To" field.
4. Optionally add others in "Cc" or "Bcc" fields.
5. Write a subject line.
6. Type your message in the body of the email.
7. Add attachments if needed.
8. Click "Send" to deliver the email to the recipient(s).

If more detailed steps are needed on either sending physical mail or email, please specify.