Speaker Upgrade

Hello! I am looking to upgrade my speaker system without spending more than I have to. I was quoted $440 for an upgrade consisting of Infinity speakers (no model specified), but I would like to complete it myself as to save money and give myself something to do. If anybody could help me out I would greatly appreciate it. I have been looking at these:

and was wondering if I need two of this item to complete the front speakers replacement as well as buying an additional two 6.5 for the rear? Also, what is the box for? I would appreciate the information before I buy. Thank you.