• Click the Compose Mail link on any Gmail screen (it's on the left, under the Gmail logo).
• Enter your recipient's email address. You can type the address in the 'To:' field, or find the address in your Contacts list.
• Enter a subject for your message in the 'Subject:' field.
• Write your message! Just click in the large field and type away.
• When you're done composing, click the Send button (located just above the 'To:' field). You'll see a confirmation at the top of the window that your message was sent.

Extras 

• You can change the formatting, font, and color of your message text using the tools located above the compose window. You can also attach files.
• We suggest using the carbon copy feature when you'd like to include additional recipients whose responses are welcome but not required. Display this field by clicking Add Cc. The blind carbon copy field (click Add Bcc to display) lets you hide recipients' addresses and names from one another.
• When you begin to type an address in the 'To:,' 'Cc:,' or 'Bcc:' fields, Gmail will suggest complete addresses from your Contacts list.
• As you compose a message, we'll automatically save drafts every few minutes so you can leave your message and come back to it later before sending it out. You can also click the Save Now button at any time to save what you've written.