Newbie Questions

I purchased the 5D and added 20TB of drives. Backed up my MacBook Pro & now wish to back up my Windows desktop. I thought I purchased to correct model to do this but for the life of me, I do not know how (without re-initializing & losing data between each machine backed up). Is there a way to do this or did I purchase the wrong product? The reason I did not select the 5N is due to slow internet connection. Any help would be appreciated.