I can't send e-mail

Welcome to the Apple Support Communities!

I understand you are unable to send an email because you can't remember the password. Who is your email account provider? Is it iCloud or Gmail or Yahoo or ....?
If @icloud.com is how your email address ends, then you have an iCloud email account which is managed by Apple. In that case, your Apple ID password is also your password for email. If you forgot it, go to your Apple ID account page and click "Forgot Apple ID or password."
If you forgot your Apple ID password
If your email provider is someone else, you would need to go to their website to reset the email password for your account. Then, you can update the password settings in the Mail application on your Mac.
If Mail on your Mac keeps asking for your password
may052, please reply to this thread with additional information and we'll be glad to help. What version of the operating system are you using on your Mac? Don't share your email address, just tell us what comes after the @ symbol in your address. We'll be happy to help!
Take care.