1. On the Navigation bar, click People.

    Note: You can find People in one of two places on the Navigation bar.

    If you're using the compact Navigation bar, click the People icon.

    Select the People icon to see your contacts.

    If you're using the expanded Navigation bar, click the word People.

    Select People to view your contacts.

  2. Under My Contacts, select the folder where you want to save the contact group. Usually, you'll select Contacts.

  3. On the Ribbon, select New Contact Group.

  4. Give your contact group a name.

  5. Click Add Members, and then add people from your address book or contacts list.

    Add members to a new group

    Note: To add someone who is not in your address book or contacts, select New E-mail Contact.

  6. Click Save & Close.

    To learn how to use your new contact group, see Send an email message to a contact group.

Instructions and imagery copied from Microsoft's support page: Create a contact group or distribution list in Outlook for PC (microsoft.com)