Advise for DAG server

I have exchange 2013 CU2, on windows server 2012 r2 and the physical machine is HP ProLiant ML310e Gen8.
Now I want to implement a DAG server, can anyone please guide me through the requirements like which machine I should purchase for the DAG and can I use windows server 2008 R2 standard. and how to make the physical connection with the existing server.
I have 1TB on existing server, does the server I implement in DAG should have the same amount of Storage.
thanks all and appreciate your assistance.