You can use photoshop to make the 50% size image. Go to admin page on your site and selest sections. You will see a text box to add an image file. As for the full size image make a link on the section page ( i think you can) to the full size image.

If you want I will make the 50% image for you. Just give me a link to it or e-mail it to me.

What I was saying is if you need a screenshot of a page on your site give me the link and I'll make it and make the 50% and give them back to you.