This wikiHow teaches you how to search for an image based on an existing image on Google
Open the Google Images page. Go to https://images.google.com/
on the right side of the search bar that's in the middle of the page.
If you want to find images that match a certain word or phrase, just type that word or phrase into the search bar and press ↵ Enter to view image results.
Click one of the following tabs: Paste image URL or Upload an image
Paste image URL- Click this tab if you copied the image's web address earlier. To copy an image's web address, open the image, click the address bar at the top of the window to select it, and press either Ctrl+C (Windows) or ⌘ Command+C (Mac).
Upload an image - Click this tab if the image that you want to use is stored on your computer.
Depending on the photo upload option you selected, this step will vary
Paste image URL - Click the search bar, press Ctrl+V (Windows) or ⌘ Command+V, and click Search by image.
Upload an image - Click Choose File, locate and click the image you want to use, and click Open.
If your photo exists elsewhere on the Internet, you will see different sizes and versions of the photo here;
if not, Google will find images that look similar to the one you uploaded.