Which operating system have you got?
If it's a new PC, the chances are that it's Windows 7, which doesn't come with a built-in email client. You need to download and install Windows Live Mail:
http://explore.live.com/windows-live-mail
Then follow these instructions, from BT's support pages, which will tell you how to set up your account:
http://bt.custhelp.co...s/s_cid/con_FURL_help
(Don't worry that those instructions are for Windows Vista. They should still apply to your system)
Once you've done that, my 'right-click' method should then work.
Chris