well, first you have to have an email account. If you already have one, then go to that account, click "compose" or "new mail" and then in the larger white box type what you want to say. click "send" which is usually toward the top. It depends on what type of email you have. Yahoo, gmail, hotmail, etc.
Hi. email is like a service and you can use more than one providers who give it. Compare everything to a real postal service. Take for example www.gmail.com and you will find an option of Signup or create account.They ask you to fill in your details and a username and assign password as you have done with this website like you have here as "12345earnie". All this is a one time process. Once you have done all this, you will have created your own email id like email@example.com or for example, firstname.lastname@example.org. Inside it you will find an option to create mail or "Compose" in case of gmail. in the "To" header, you must have the address of the person you want to mail in the format email@example.com or firstname.lastname@example.org or whatever. In the body, you type in content which you want to write and after all is done, you can find a send option somewhere near the top row. I hope this is elaborate enough. Was not sure about how much you know.Revert if you still have doubts.