How To Create Blog

Hello,
I want to know if it is okay to quote a blockquote from a book to post in your blog/website? Reason I ask this is because I find some interesting stuff in a book and want to quote it into my blog/website. I want to make sure it isn’t against the copyright.

I include the author’s name and the book I get the quote in the footnote though. I dunno if it is still against copyright or not.

Another one that is similar to this question is I want to quote a story from a book and use it to make a study guide that will be shown on my website, is that okay? For exmaple: I want to quote a story, and then write down a list of definitions for the vocabulary words from that story. That way it helps me study as well as others.

My biggest concern is if it is against copyright or what.
Please help, thanks in advance.
Yes. I will be credit the references. Reason I have doubt is because I remember reading from a general Open Letter from the author in a book. They always state thanks to X author for giving the permissions to allow them to quote it. So I was wondering if I have to contact the author to quote it or not.

Thanks for the information!
There are some parts where it is only 1 or 2 sentences. But there are also part where I like a lot which is like.. well, it is like a paragraph. Is that still fine?

Thanks.