How to store picture in a directory

Hi there,
im working with a java project which need to load an image into a panel. I have tried various coding. The application only displayed empty panel. Currently i stored the image in a package folder of a java class file. I understand, that image need to be stored in a directory(which directory it refering to??)... but i have no idea how to do that. I also want know, whether is it appropriate to put the image in a package folder? i also tried the coding provided in this forum...but i get nullpointer exception. So, i think i have placed the image wrongly. Pls guide me on how to store the image at appropriate path and load the image successfully. Thank You