To modify the membership of a distribution group that you manage, follow these steps.
1. Open Microsoft Outlook
2. Click on "address book" in the ribbon
3. Search for the group that you want to modify and double click on it.
4. Note the owner listed. If this is not you, then you will not be able to modify the group. Click "Modify Members"
5. To remove someone, click on their name and click remove. To add someone, click the "add" button
6. Type the last name of the person you wish to add and click "go". Click once on the person's name in the list, and then click the "add->" button, and then click OK.
7. Click OK two more times