The ARRAY command has changed dramatically in AutoCAD 2012.Gone is the dialog box that you've been used to for year. Instead, you get a slightly trickier and more powerful Array command. This video just deals with the Rectangular option. The second part of the Array command video for the Polar and Path options can be found here.
After watching this video you might find that you don't want to change to the new Array command right away. There is a download you can get that will give you the old Array dialog box back. This creates a 'CLASSICARRAY' command.