Hello,
I am just starting with Krita. Never have used digital painting programs. Most you tube tutorials assume you know how to turn the thing on, I have gotten that far, but when trying to do a lesson using the lasso tool, I find that I cannot unselect it. Does anyone know of a tutor? Thanks Ginny M

On the top bar with the "File" "edit" and other options, there's a "select" dropdown menu which will have an option to delesect all. Another way to deselect all is to switch to the magic wand tool and tap off the canvas in the gray.

If you just want to deselect a certain part, you can go to the "tool options" docker in the sidebar and switch to the subtract setting, where you can deselect what you want but not everything.

Whatever tool you're using, the Tool Options docker is very useful and should always be enabled so you can see all the available options and select/control them.

I suggest that as well as YouTube and various written tutorials, you read the manual and play with it to see all the things that can be done: https://docs.krita.org/en/ It's well written and has a good Search facility. Play with it and enjoy it and come back here if you have any problems or misunderstandings, which you will.

Thanks everyone, I will go and try the suggested solutions and read the manual.