Don't have Outlook, have OE.
In OE go to your address book, Click New and choose NEW GROUP.
This opens another box. Give the Group a name.
Then add names to the group by clicking select members. You can choose any or all of the names already in your address book, or you can add new ones.
Once the Group is created it appears with a different icon in the Address list to the left.
Click in it to create an email to all the group, or click create mail and type the group name into the To: box.
I assume this will work with Outlook.