I just downloaded Krita, and after I made a new project, I tried drawing but nothing came. I chose the colour red but still did not work. (Windows 10)

Which brush preset are you using? Are you using a mouse or a graphics tablet+pen?

Are you sure you're drawing on a paint layer and not a locked background layer?

Have you made any changes to the default settings and configuratiom of krita?

Can you post a link to a screenshot of krita as it exhibits this problem? (Use imgur or a similar posting site, etc).