Lightbox assistance please

I would like to have a thumb of each image on a page and click on it for a overlay of that image.

I have searched plugins and found numerous but cannot seem to make any of them work for me. Most all just say install and activate and that is all that is necessary but it seems to me that code should be required via html to point to the location of the image but for the life of me I cannot find what code to use on any of them.

I was using easy fancy box and it worked for a fashion then suddenly all I get is the image coming up on a whole new page which is not very pleasing to the viewer.

Does anyone have a suggestion on what plugin to use and what the sample code is? I need nothing really fancy.

Stumped in Oregon