No you can post pictures directly from your computer. You have to use the 'Reply to this Thread' button instead of the quick reply button, then there's a paperclip that lets you download a picture. (or upload).
So the blanket is very chunky yarn, or several strands held together knit on huge needles in a cable pattern. You can try searching for a similar cable pattern - here's a link
for a cable stitch gallery - then figure out how many sts per inch (or inches per stitch..) and multiply it time the size you want. You would have to adjust the stitches to match the repeats in the cable pattern, plus edge stitches.