you can edit the settings at google images to find copyright free pictures.
Go to google images and type in your search.
Pictures show up, under the search field there is a line "all, pictures, news ... settings, filter .
Click on filter. A second line pops up
size, color, user rights, type, time
Click on User Rights
"marked as usable in non-commercial ways" (or something in that sense, I don't know the English wording).
Check that, and the pics that pop up are usable