I could tell you about my experience. First, I wrote a book but I wanted to post it where readers could potentially find it. Wattpad seemed good, there are a lot of readers on here but sometimes you have to bug them with an advertisement (which is discouraged, Wattpad says. Unless the user states it's okay.)
Wattpad was designed for what's called serialized books, meaning that you divide your book into chapters and post them regularly (maybe 2 chapters every Saturday) until the story is over. This was the approach I took, but I could have uploaded my whole book at once, too.
I uploaded a cover for my book, wrote a description, and then added tags.
Tags,--if I hadn't eaten too much oatmeal pies lately--are like categories for your book that help readers narrow down a search and find it easier. So since I wrote a jungle book, I tried to think of jungle-related tags (Jungle, Rual, Woods, etc.) It's also christian fiction, action adventure, it contains sisters, and it's a novella, so I tried tagging my book with those.
I think you can rank in each tag, too. What I mean is that you may rank #1 in Jungle while you're ranking #200 in Fiction. This is algorithm based and will change constantly. The higher you rank, the more possible you're book will be seen when someone searches for that tag. If my explanations make any sense, lol.
And genres? Like cake! Genres are different from tags but in my opinion they overlap. They're like the overall topic your book fits into. My jungle book would fit perfectly into a few genres Wattpad offers, but I think I chose Action Adventure, or something because that's what the book is all about, to say the least.
I guess, tags expound on genres. Like the finishing touches on a cake! Yeah, my sweet tooth lately, lol.
