Help

Recently I found out I can make some money by selling my art as NFT. I have a few questions.

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1. can you explain what NFT is? I did a lot of research and still don't get it.
2. can I still sell them even when they includes stock images that are not mine?
3. I know nothing (by nothing I mean really nothing.. zero) about crypto money stuff. will that be a problem? and if that's so where can I learn about it?

Thanks a lot! 🙂