1. In a web browser, navigate to portal.office.com, sign in, select Outlook.

    A screenshot of portal.office.com showing the link to outlook in O365

  2. Under the Groups section, select the name of the group.

    A screenshot of the Groups menu on Outlook for Office 365

  3. In the top right corner of the window, click on the members section.

    A screenshot of the link to the members section link on the groups management page in Office 365

  4. Select Add Members.

    A Screenshot of the add members icon for Groups management

  5. Enter the names of the members to add.

    A screenshot of the Add members dialogue for Groups Management

  6. Select Save in the top left corner of the pane.