My Hero Academia Prompts - Tumblr Posts

I could be overthinking on how to do this, but does anyone know how to make a prompt list for fanfiction? This would be for My Hero Academia specifically.

I am in a rare pair mood and I have an idea for prompts for January. With it being the first month, I figure the prompts could be “First Meeting”, “First Kiss”, “First Fight”, etc.

But I do not know how to make a prompt list here on Tumblr, or how to make a spot where people can turn in their work on AO3, the site I have in mind. Can anyone help explain how I can do so?