How to make to my NPC reading a book when sitting???

Help!!!)

You need to look at packages. There are some video tutorials in the video tutorials thread, and also written ones on the wiki.

Create a new package for your NPC, select "Sit" as template. "Under the "Idles" tab, check "Use Specific Idles" and select two new idles: IdleBookSitting_Reading and IdleBookSitting_TurnManyPages. (Right click in the blank area), check "Random" at the bottom.
If you want your NPC to sit on a special chair, just select a chair under the "Package" tab (Under "Search criteria" Click "Furniture" on the right, Check "Specific Reference" and "Select Reference in Render Window") You should set your NPC as owner for that chair, to make sure only he can use it.