Dropdown List for user to select - Simple code if possible please

Hi everyone. I am very new to NX Journaling and am looking for a way to create a dialog box with a dropdown list that displays part numbers of the components in the assembly for the user to select and click OK. I have found some code but they are quite lengthy and difficult to follow. Can someone please come up with a simple code only related to creation of the drop down list. Thanks in advance.