Connecting two wAP's with output via ethernet port

Hi all,

I just got my two wAP’s that I want to connect together. Explained further:

One wAP is connected to the internet via its RJ45 ethernet port and works as a normal AP. The second is located on another rooftop that would need to pick up the signal from the 1st wAP (they overlap with about 80% coverage so that is no issue) and then forward the internet connection onwards via the RJ45 ethernet that would be plugged into a switch and then used by the stationary PC’s.

So for the first part setting up the 1st wAP was a piece of cake, the second one I have no idea how to “switch” the internet input from Ethernet to Wifi and output from Wifi to ethernet.

Any tips greatly appreciated.