I’m just not understanding – custome fields. HELP!

Ok, I’m an average HTLM/web designer. Some things I get, and some I don’t. Ya got me on this custome fields stuff!

Here’s what I want to do:

I’m posting my poetry, and want a field that can be updated/edited on the fly to denote if the original has been edited, like:

Plans To Revise/Edit Poem? No / Yes / Never; final version

I’d like this to be included only in my POETRY category

How can I successfully accomplish this feat? Is there a plugin that can do this? I appreciate any help you might be able to give, and you have my thanks in advance! Oh, and I am using a theme.

~ R.T.