I get an error when upgrading from xcode 4.3.2 to 4.5.2

Question

I have Mac OS X v10.7.5 Lion. I am trying to install Ruby 1.9.3. At runtime, I just downloaded xcode 4.5.2 to replace 4.3.2. But when I do this, I get the following error. How can I fix the problem?

Thanks in advance.

The operation can't be completed because some items had to be skipped. For each item, choose File > Get Info, make sure "Locked" is deselected, and then check the Sharing & Permissions section. When you are sure the items are unlocked and not designated as Read Only or No Access, try again. 

Answer 1

I found that first I need to remove the old one and put the new one in the applications.