Connie, as I said in response to your other comment:
The recent El Capitan upgrade added some improvements to Photos. There is still not a full support for batch changing, but we can at least select multiple photos at once and add the same title or caption to all selected photos at once. Simply open the Info panel after you select the photos and type a new title or caption into the Info panel. It will be changed for all selected photos. You can also change the location for all photos at once this way.
Photos is not a stand-alone application, that is updated separately. It is installed by MacOS X, is a part of the system software, and any update to Photos is only available by updating the system. So, if you want to profit from updates to Photos (better sorting, geocoding, changing multiple titles and captions), you have to upgrade to El Capitan.
Or simply continue to use iPhoto, if you prefer it to Photos. The compatibility update iPhoto 9.6.1 for Yosemite is working very well on Yosemite and Photos.
On Yosemite you can use the AppleScripts we posted to add functionality to Photos.
User Tips: Photos for Mac
Batch Changes in Photos for Mac: Change the titles to a Given String
Photos for Mac: Batch Change the Date and Time to a Fixed Date
Photos for Mac: Batch Changing the Titles to the Filename
Photos for Mac: Batch Change the Descriptions