If you are using an email client such as Outlook Express, Eudora or other, you can easily find the required data in the settings of your client. Open your email client. Go to Tools -> Accounts. Click on your account, then click on properties. In the General tab you'll find the email address.
Click on Servers tab. Copy your server's name, then the username and password, and fill in the required fields in Email Autoresponder's settings.
If the box next to "My Server requires authentication" is marked, click Settings.
You'll see the following window. Take the username and the password from the marked fields.