Can I install icloud on myimac that is 7 years old

To install iCloud need the Mac must be running 10.7.5 at least

iMacs from 2007 and later can run Mavericks if they currently have 10.7.5 or later installed as Allan pointed out.

If it's an 2006 iMac it can't run Mavericks.

OT

If you have a 2006 Mac you may be able install Lion (10.7) which includes iCloud.

Here are the minimum requirements.

OS X Lion system requirements

To use Lion, make sure your computer has the following:

• An Intel Core 2 Duo, Core i3, Core i5, Core i7, or Xeon processor
• Mac OS X v10.6.6 or later to install via the Mac App Store (v10.6.8 recommended); you can install without Mac OS X v10.6 by using an OS X Lion USB Thumb Drive, available on the Apple Online Store
• 7 GB of available disk space
• 2 GB of RAM

If your Mac does not meet these requirements, you will need to upgrade your Mac before installing Lion.