Log in to Twitter.
Click in to your Profile
Edit Your Profile
Clicking profile again will show your profile (http://twitter.com/settings/profile)
Your Name, Location and Website are shown.
Under website address there is a link to show twitter on your site, click this and you can choose which widget to display.
The widget can be customised as required.
Click "Finish and Grab Code" at the bottom of the page
Copy all the code from the text box.
In your website extranet, edit the page you wish to put the widget, or the snippet you wish to display the widget.
Switch to HTML view by clicking HTML at the bottom of the WYSIWYG editor.
Paste the code, save the page
Your twitter widget will now appear on the selected page ( or all pages if a snippet was used)