The ebooks category is for legitimate self-publishers to provide a listing for the promotion of their ebooks. TMB is only to host the listings, not get involved in payment nor host ebook files.
The listing must include a sample chapter. Your listing may include cover art / banners, descriptions, and the links to download the ebook. It must be listed ONLY in the category 'ebooks' - not in additional categories like original, nonfiction, etc. You may also not list ebooks in those categories, those are for stories hosted and displayed free on TMB only, and readers need to be able to browse without getting 'ads'. The other info, like genres / ratings, may be included. Ebook listings are subject to moderation and may be reviewed like other writings.
Mods are going to be strict in regards to listings. This keeps out spammers, lousy 'marketing', ebooks that are 150 words, stolen public-domain books, bad links to viruses and malware sites, and in general encourages real buyers for the serious authors. If it is a free ebook we are going to be looking at how good it is. If you are caught spamming you get a warning or suspended, based on what the listing included. It is very possible that if your stories get approved your listing for an ebook might get rejected.
You must own the rights to publish the ebook.
It must be an actual ebook file too, not a link to a story on your websites.