How can I open a image once click a buttion during game?

Hello everybody, here I have a question that how can I open a image like “map” when I click a button?
Should I use GUI.window?

Use a gui.label with the texture override. You can insert the label into a window if you wish, but it’s not necessary. Using gui.dragwindow would allow the end user to move the image about, if that’s desired for your user interface.