Within the selected template, click on the gray background labeled "Image," "Image or Video," or "Photo." This section always includes an image icon. If you don’t see one, it means you cannot add a photo to this slide.
This will open your files, allowing you to select the desired image. Once selected, a window will appear, allowing you to crop and/or resize the image.
Click the cross in the top-right corner of the window. Congratulations! Your photo has now been successfully added !