Clean install of elementary os. Ticked box during installation to download software. Apparently didn't work. I have about 12 apps installed. No gimp. Terminal commands to install repository not working. No sudo commands working. On the whole, very displeased!
Elementary will not install Gimp, or any other third party app, during install. Elementary has it's custom apps that are installed and everything else is left to the user to install. But it's very easy through the App Center or via the command line.
Elementary is also not setup to add PPAs by default for security/usability reasons.
You can set your system up to add PPAs by running:
sudo apt install software-properties-common python3-software- properties python-software-properties
I hope this helps! Elementary really is a fantastic OS with a great community. You should stick around 👍
First, you must update your system.
sudo apt update && sudo apt upgrade
Then for install any other application you can use AppCenter, like gimp or anything else.
You can also install deb packages on your system using the gdebi installer.
sudo apt install gdebi
If you want to use PPAs, you can follow Pretzel Jones's recommendation.
Have a nice day.