Step one: Search Google Images for something. I typed in Taco Stand.
Then I scroll over to the right to this row of buttons:
Click on Advanced Search - you'll go to this page:
Scroll down the page and you'll see these options:
Click on the bottom choice, Usage Rights and you'll get these options:
Since my site is not a commercial site (nothing for sale), I click on free to use or share. If you want to change the photo, click on free to use share or modify. Here are the results for Taco Stand after my search. I can feel confident using any of these photos on my blog.
I hope this helps - sometimes the photos are limited or weirdly related to your search, but it is a really helpful tool and for me, sometimes easier than going to a stock photo site.