You can always upload a new version, or replace the previous version by editing the post, as you like, Strether.
As for submitting it, basically just start an new thread in this sub-forum:
https://www.mobileread.com/forums/forumdisplay.php?f=126
You can look at the existing ones if you'd like an idea of what others have done. It's been suggested (in the interest of being able to find stuff later) that they be posted with the thread titled in the format: Author's Last Name, Author's First Name: Book Title.
I suppose that information would make a good "sticky" at the top of the Sub-Forum.