@****y6, no stress, this is exactly what this group is for - getting help from fellow moderators.
To change your group profile and cover art, the steps are:
• Go to your Group start page
• Click on "Administration" and choose "Group"
• The third section down ("Display in Group Overview") has "Image or logo" and "Cover art", where you can put those. To the best of my knowledge, the ideal sizes are 200x150 for the logo and 965x200 for the cover art.
• Don't forget to hit "Save Group" at the bottom of the page when you uploaded the art.
It will take a few minutes for the images to show everywhere.