GIMP is an Open Source free raster photo editing tool tool. (Adobe Photoshop Alternative)
We use it for photos, thank you letters, posters, etc
On a PC or a Mac go to https://www.gimp.org/downloads/ to download and install on you computer.
Because GIMP is a thicc application that must be installed on your PC you will want to Install Google Drive Sync so you can share your art and designs with the Teams Google Drive.
Go to https://www.google.com/drive/download/ to download and install google drive sync for your Mac or PC. log in with what ever google account you are using with the team.
a raster image is made from pixels a vector image is made from lines, basicly if you zoom in on a raster image it starts looking ugly and pixelated while a vector image looks smooth but just gets bigger.
a good explanation on raster vs vector is here
Their website keeps many text based tutorials https://www.gimp.org/tutorials/
https://docs.gimp.org/quickreference/gimp-keys-en.pdf