how do i get my apps from my ipad onto my imac? i am logging into itunes but cannot get apps

You do realize that the apps for the iPad cannot be used on the Mac, right? They are two different operating systems. iOS apps for iOS devices and Mac Apps for Macs.

You can only store iOS apps in the iTunes libraries on a Mac.

How to transfer or sync content to your computer -

http://support.apple.com/kb/HT1296

Go to the  menu in the upper left and choose App Store. You will then open the Mac App Store with apps for Macs.