Hi
Open Google Images and search for what you want. Hover the mouse over the image you are interested in and the size will be shown
Click the image on the main search page to open it .
Right click it and select "Copy". (You can also click "Properties" first to check that the size is what you want.)
Open a suitable folder, right click and select "Paste."
You can also click the little"Show Desktop" button on the bottom toolbar and paste it there before coming back to Google.
Nat