You'll have to provide some information about yourself, as well as choose an account name and password. Your account name or ID becomes part of your e-mail address. If you're lucky, no one else will have it. Since e-mail may contain sensitive information, it's important to have a secure account that only you can access. Choose a password carefully.
Passwords are usually case sensitive, meaning that they use both upper and lower case letters.
Changing your password every few months is a good idea, too. For more help read our Password article. As we come to depend more on e-mail for business and personal communications, having reliable, trustworthy access is critical. You will have to evaluate each service on its track record. A few services stand out for their longevity, reliability and friendliness.