Before you go any further make sure you have tried your best to find images within Drive, WeVideo, etc. Apps like Docs, Slides, and Drawing have an “Insert -> Images -> Search the web” option that will give you high quality, free to use images. Always start there. WeVideo has a built-in library of thousands of images that are also high quality and free to use. Always start with the built-in options. Searching Google outside of an app should be a last resort.
Also, remember, there are only 2 things on the internet
If you can’t find images within Google Docs, Slides, or Drawing… or if you can’t find good images inside of WeVideo… then you can do a Google search.
Search for your topic; start simple and broad in terms, don’t put too many words in your search.
When you search for your topic, click Images, then click Tools
Change Size to Large and change Usage Rights to Creative Commons
Find the one you like, click on it to see the full size version. Alt-click (Chromebook) or Control-click (Mac) on the large image and choose Save image as
On a Chromebook you can have it download to your folder in Drive. On a Mac it will download to the Downloads folder (on a Mac you can then upload to Drive if you want).
In WeVideo, click Import and choose the location where you saved the photo, or drag the image from your Downloads folder.