There's no standard methodology to gather email addresses. For example, when you move, your new phone number is listed in a phonebook. There is no such service for email address. The good news is however, that if you want your email address posted for others to find, most databases will allow you to do so. Just remember, that if you post your email address out, not only can your friends find you, but also, direct marketers and others whom you may not want to find you.
Email is the same as regular mail, except it's faster, and more standardized.
OK, I think we have etiquette cleared up now. Time to learn how to email. Sending email is pretty simple. Using whatever program you have select new message. Each email program has a different way of handling an address book.