NOTE: If you do not see the toolbar (ribbon) in your Outlook, your ribbon may be hidden. To enable the ribbon again, follow the instructions posted here.
Name the group
Click on the arrow to the right of Add Members and select From Address Book
Enter the user’s name you want to add last name, first (e.g. Bob, Billy)
Select the user you want to add
Click the Members button at the bottom left
You can continue adding users from the global address book by searching for them, selecting them and hitting the member button
Once you have added all the users click the OK button
If the user is in your contact list then when you click the arrow to the right of Add Members and select From Outlook Contacts
You search the same way you did in the step 6 above
When you have completed adding all members, click Save & Close.