If you need to resize the images, just follow this link and download the free software. Safe and easy to use. Once you have it loaded you simply click the image you want, click to convert and have it save to same location. Thus if you have a folder with pics of the car called for sake of argument, "front", "side" and "back", you would then have a folder with 3 extra pictures called "front - 1", "side - 1" and "back - 1". The "- 1" files are reduced and can then be uploaded to here.
http://pixillion.en.softonic.com/