Once you've completed the 3rd step, you will be redirected to the download page where you will download your picture. Step 3: click the 'overlay picture' button.Simply verify that the image is in either jpg, gif or png format. You can use any picture that you'd like since the tool will automatically adjust to fit landscape as well as portrait photos. Step 1: choose the country flag that you want overlaying your picture.Using the 'Flag Overlay Picture Tool' you can easily overlay your picture with a country flag using the three steps below: