You can use the google search engine to filter results by usage rights. Do so, and when you find an appropriate picture, visit the website where it's featured. Look for the copyright terms and notice, google possibly identified it as creative commons or free copyright (and hence the listing).
If you found an appropriate photo with a copyright that allows you usage, import it to HubPages. Most kinds of creative copyrights require that you backlink to the original page, which you can do by providing the link in the 'url' section of the Hub's capsule.
Finally, find the author of the original picture and input their name, along with any company they'd be in and the name of the website into the 'name of the author' part of the Hub capsule. If you do it such, I don't think you'll receive any copyright complaints.
The main thing is to filter image search by copyright and use pictures that are 're-usable', with a clear copyright notice on their websites of origin.
You will notice that about half the pictures you'll find on google like that stem from Wikimedia Commons. That's fine, because Wiki Commons has a concise and easy display for both copyright, author name and source websites that you can pull over to your hub. Wikimedia Commons also has most copyright definitions at hand for you to read and comprehend.