Here is one approach to a gallery:
Start by making three sizes of each image: One 800 pixels wide, One 450 pixels wide and one 75 pixels square.
Create a thumbnail grid. Make a link from each thumbnail to a different page (i.e: <a href="image1.html">
and <a href="image2.html" > etc, until all the thumbnails have links. Put a larger version of the first image in the main cotent area and save the page as Image1.html; then replace that image with the second large image and resae the file as "image2.html, and so forth, until you have one page for each thumbnail link. Test your pages.
You can make the large image in the page link to an even larger view tht opens in a new window. <a href="LargeImage1.jpg" target="blank">
