join sites on different network

Hi my name is saleem shaikh . I am a student and eager to learn servers and i am learning ws 2012r2 . I need help with how can i join 2 different networks.

Scenario i have is : I have a DC with ip address [ 192.168.22.3 ] on Site 1 AND a

                             ADC with a IP address [ 192.168.21.3 ] on site 2 .

I will be very thank full if you can share what are the important steps i need to do for joining any server wether a ADC or DC on different networks.

Thanks & Regards

Saleem Shaikh.