Does anyone know about picture editing software called paint.net? or something similair?

ok so my sister just downloaded this software for pictures where you can add a layer of black and white and erase some of it and it will show the original color..she said she found it on cafemom but i dont have one and i looked it up but i dont want to download something that isnt right..can someone show me a website that has that..Does anyone know about picture editing software called paint.net? or something similair?
The official homepage for it is http://www.getpaint.net/ and it's safe to download from there. You can also try using Gimp.

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