Source MyPaint Homepage.
It sports an intuitive interface that offers quick access to the main functions of the program. A special emphasis is put on the working environment which is clean and gives you the possibility to focus solely on the drawing process
To install MyPaint just run the following commands via your systems Terminal.
sudo add-apt-repository ppa:achadwick/mypaint-testing
sudo apt-get update
sudo apt-get install mypaint mypaint-data-extras
That's it enjoy!