Slab design in staad pro.

Hello I'm just a beginner in staad pro. I'm trying to design a 6-storey building. After analyzing the structure i used commands option to perform concrete design. It gave me reinforcing details for column and beam. But not for slab. I added plates for slabs and perform quadrilateral surface meshing.(I read that in a tutorial I don't even know what surface meshing is) My questions are:

1) What should I do to design slab? 2) Can i perform calculation of lift and stairs in staad pro? if so then how?  Please take a look at my file and point out any error.

Thanks and appreciation in advance for help.