Zend certified PHP/Magento developer

How to connect two magento2 application

I have two magento2 application running which are M2(a) and M2(b), I want all product on M2(a) to be displaying on M2(b) automatically, I have created an Integration on M2(a) by going to admin->systems->Integration. and now i don’t know how to call the key generated on M2(a) and integrate it on M2(b).
Any assistance will be highly appreciated