Hi, how can i create a profile book and a aboute me tab.

The profile book is a plugin. It is used on this site but it has not been released yet.

The about me page you can create with by creating the tab and then adding the fields. If you havn't done this already you could go to community builder and then click on tools. Click the load sample date link. It will load a tab called "additional info". It will not show up on the profile until you enter some of the reqested details in the update profile. Anyway you could change the name to "About Me" and then add and edit the fields that are already there.

what is a profile book?

I guess it's a guest book. You have one on your joomlapolis profile. It is used for people to say they stopped by and checked you out.