Install IExif by running the setup file that you downloaded from the home page, and follow the wizard instructions.
Don't forget to confirm activation of the add-on by the Enable button at the bottom of the Internet Explorer window, and re-start browser.
After you installed IExif you can test how it works on special sample page that contains single photo image with EXIF metadata. When the page is fully loaded, position the mouse cursor over the photo. If the add-on was correctly installed you will see the popup tooltip window containing all the collected EXIF information.
After that, if you assured the add-on works well, you can navigate to any other web site containing photos, taken by digital cameras. For example: it can be any of online forums or the personal site of the photographer you like.
As you recently did on the test page, find the interesting photo on the website that you currently viewing and position the mouse pointer over the image. If the photography contains EXIF metadata, they will be displayed in the small tooltip window.
If the tooltip does not appear or contains no EXIF data, do not be discouraged! It is possible that the viewed photo does not have EXIF information inside. For example: most of popular photo-hosting sites cuts off EXIF data from the uploaded files (but sometimes it persists in original large images). Some other web sites may use too complex method of pre-loading images that still cannot be traced by the add-on. We keep working on it ;)