Download and install Krita, the free professional painting software. Visit krita.org and select the installer for your OS (Windows, macOS, or Linux). Run the installer and launch Krita. Create a new document: File > New, set canvas size to 2000x2000 pixels at 300 DPI. Optionally, connect a drawing tablet like XP-Pen Deco for better control, but start with a mouse if needed.
Explore the default workspace: Dockers (layers, brushes) on right, toolbox on left, canvas center.