Email Address Access

[#1]

I am new today with PLUSNET and am confused with email addresses.  I have my address that i chose when i signed up and as there are two children in my house i want an email address for each of them as well. After adding two other addresses and passwords as 'mailboxes'  how do i get to them, i can get to mine on the plusnet site webmail but not the other two, i have can also use mine on windows live.  Im probably just being dumb here but as my username suggests im abit behind the times with I.T.  By the way we are on vista and have 3 computers in the house.  PLEASE CAN ANYONE HELP?!
dick:red Title in full capitals edited as per forum rules

[#2]

Hi there,
To log in to the additional mailboxes via webmail you need to enter the username in the following format username+mailbox.
So if my main account was chris@exampleusername.plus.com and I set up a mailbox called fred@exampleusername.plus.com I'd need to enter exampleusername+fred to log in to the fred mailbox.

[#3]

Thank You very much for your help. Its now sorted
p.s. sorry about the capital letters, didnt realise there was a rule about them