please help w\ mailbox quest

The voicemail option has nothing to do with phone operation, which is why the manual doesn't say anything about it.

All you need to do is press and hold "1". This should take you into the AT&T Voicemail system, which will then instruct you how to set it up.

 

Welcome to WA angelamarie. Here is a link to setting up & using your VM, it's very simple but in case you want more information I figured this would help.

Voicemail | AT&T wireless services

As for getting your messages, if you get a message it will say "View or Ignore" on the screen, the left top button is for View & the right top button is for ignore.
Also you can hit the top left button on the home screen (also called a soft button) to get into the "Menu" then select the # 2 button and that will take you into the message option screen to read your messages as well as your sent messages or more.

I hope this helps & feel free to ask more questions if you need more help.