if I bookmark a chapter, where can I see when there is a update??

Mark as " read " or " is reading" so you can get notified it's getting updated. I don't think bookmarking notifies you, but could be wrong.

The bookmark function works as a real life bookmark. It just marks which page/chapter you stopped reading it, so you can find it back later. You've to mark the manga as "now reading" to get notifications

thank you :)