Q: imac OS X 10.7.5 with iPhoto 9 8.1.2   How do I update so I can stream photos from other devices?

If you're referring to using the My Photo Stream read these Apple documents for requirements:  System requirements for iCloud - Apple Support  and  My Photo Stream FAQ - Apple Support.

This is what is required from My Photo Stream (from the first link):

My Photo Stream

iOS 5.1

OS X Lion v10.7.5 iPhoto ’11 (9.2.2) or Aperture 3.2.3

To get iPhoto 9.4.3 (the highest version of iPhoto 9 that will run on 10.7.5)  purchase a copy of the iLIfe 11 disk from a 3rd party retailer like Amazon.com or eBay.com.  That will install iPhoto 9.0 and you can get to 9.4.3 vis these updaters:

1 - update to iPhoto 9.2.1

2 - update to iPhoto 9.3

3 - update to iPhoto 9.3.2

4 - update to iPhoto 9.4

5 - and finally to iPhoto 9.4.3