How do i setup a large area wireless access with more than 2 wl routers?

I am trying to install wireless access for a college dorn. There are 3 floors plus a basement. I have a wireless router on each floor.
Linksys (2) and Tp Link (2).
The basement Linksys is connected to the cable modem and a cat5 cable goes to the linksys on the ground level. From there I have cables going from the floor level to each of the other floors to the TP Links routers.
I can see the routers on each floor but they do not have internet all the time.
What do I need to do to make this work?