If a friend sends you a letter and includes his/her e-mail address..., Netscape will allow you to enter the address from the keyboard, and store it with your other e-mail addresses.

To access your e-mail Address Book:

From the Netscape Mail Window Toolbar..., "Click-on" Window, then Address Book.

From the Address Book Toolbar..., Choose Item, then Add User.

The Address Book Properties Tab will "Pop-up"

Fill the Fields (Name, E-Mail Address, Description) with the proper information.
Note that a "nick name" is optional (unless you are creating a list of names)

"Click-on" OK

Netscape will include the address in the Address Book.