If you want to simply copy some files, yeah just plug them in, copy and paste, nothing to it.
If you are talking about moving your OS, applications, everything to another drive, then you must use a software solution capable of "mirroring" your drive to another drive. Acronis True Image is one, there is a 30 day free trial download, and it works great, step by step instructions, very easy program to use.
If you are talking about using more than 1 drive at the same time like 1 larger drive for speed or storage, then you want to look into what is called RAID. There is a whole world of information you must sift through about RAID though, and Google is your friend to find it.