Linking an image to a google search result is not crediting the artist/photographer. At the very least you should visit the page you found it and provide that link.

Usually you can find the original source within 15-20 seconds you can simply copy over, but ideally you can try using this:

https://www.google.com/advanced_image_search

Put your search term in the top but down at the bottom you can select what kind of license in 'usage rights'. Choose 'free to use or share, even commercially'

Good luck!