I have no idea about shear force that how can i used it.also confused about bending moment when i try to construct slab or beam
It’s complicated. Unlike wood joists and beams, concrete slabs and beams often are in “double bending”. That is to say, compression will be on the bottom and tension on top.
Determining EXACTLY where that occurs in a slab or beam is complicated and you’ll need an architect or structural engineer to help.