Don't forget to make sure that you add a ZiLink Super Block to the page first and then configure that block to display the Icon Navigation block.
There is a small default set of images supplied with ZiLink but your school will probably want to create their own.
If you want to include your own images, go to the file system on your Moodle server and navigate to blocks/zilink/pix/icon_navigation and create a folder under icon_navigation. The name of the folder will the name of your set of images. Then upload all your images to that new folder.
Match the subject and image
Select the image from the drop-down list to go with the subject. It's a good idea to name your images s they are easy to identify for each subject.
Create the Icon Navigation block for your users to use
Add a new ZiLink Super Block to a location in your Moodle site such as the front page or default my home page. Click configure on the new block and select Icon Navigation from the drop-down list. Select your options for displaying the block and click 'Save changes'.