I cannot tell what they are as I need to scroll 2 or 3 pages wide..
You should resize them to abour 600 or 800 wide depending on what you're selling, then reduce the JPG compression to suit the file size (the resize already reduces it)
open in paint resize image to 90 per cent will do it a treat .the method used there in the grainey is to reduce comression and quality leaving less info..resulting in the blockiness...i think.