You will have to use the available manuals posted on various websites through Google Search, because there is no information related to this procedure. The built-in manual should provide help as well. You can access it through Help > Contents or visit the installation folder of Erdas. There should be PDF manuals with the information you need. Unfortunately, this is the only way to solve this issue. The websites you find on Google lead to studies and examples on how to use Erdas Imagine.