If you put your cursor on the small image after a few sec's it will say 'click for larger image'......do it!

...copy and paste the http address into your post, deleting the other one of course.
From the start, pick an image, put the cursor on it and right click, then click on 'view image' or 'copyURL address', this isolates the image with its own URL which you then copy and paste into the box in the article image menu.
Lately google images has changed its format. when you click on image now, you get a big black background with loads of options, 'view image' has its own box, if you're not happy with the size of image at that point, click on the image dimensions which will be written usually upper right.
Its about copy and pasting the right address mate, have a play, you'll get it, just delete it and try again if it comes out boss-eyed. If you need a key by key tutorial, when you've got time I'll do one via PM with you.
EDIT - Just seen Spurfs post, yes you must untick that tiny box, I was assuming everyone knew that.