Nelson in bondage,
I will abandon the effort if it looks likely to cost more than £10.
My source is Ian Dean's How to create an NFT for free (2022).
I chose four images to add to social media in RT3, I'll choose one of those for this exercise, Nelson in Bondage: it would have been the furtive John Soane museum picture, but as photography is banned there, that might cause offence and litigation.
Following directions in Dean's article, I:
1. opened an account in Metamask
2. and then in Rarible, fig. B1
3. note that you have to link Rarible to Metamask before personalising it
4. then the create button is available to upload the piece
5. I struggled to decide whether to set a fixed price or an auction, finally deciding on the latter fig. B2
6. AND DON'T FORGET TO SET IT TO FREE MINTING
Here it is, fig. B3. I'll take the auction down after a while.