Add Members to an Email Group
There are multiple types of email groups that have members added in different ways.
Add members as an owner
If you are set as the Owner of a group by Help Desk you should be able to add members yourself through Outlook.
Within the Outlook (Desktop) app, scroll down in your left folder list until you see 'Groups'. It may state that you are not in any joined groups. This is normal for our environment and you will still be able to find and add members to your group. Right click 'Groups' and then 'Browse Groups'.

You should see a window pop up that allows you to search for the group. You want to enter in the name of your group (not the full email). Click the view button to the right of your group.

Outlook should change to a page specifically for this group. On the top toolbar you will see a 'Group Settings' option. Click this and then 'Add Members'.

Finally, you will see a window where you are able to search and add new members. Make sure to click OK after adding anyone to the group.
