On the laptop, log into Google photos (using your Google account details).
Click 'Upload' and select 'Computer'.
Navigate to the location of your images.
Press Ctrl and A together to select all of them. (If there's a massive number it might be better to select just a subset. You can select a block of images by clicking on the first one and then holding the Shift key down when you click on the last one. Or you can select lots of individual images together by holding the Ctrl key down as you click on each image in turn)
Click 'Open' to upload your images.