The command is available when you are working in the image pool editor. It inserts a new image file in a new line above the one where currently the focus is on. It opens the edit field for entering the path of the image file in the column (for example D:\project1\icon_xy.bmp). Click the button to open the dialog box for this purpose. You can insert images in format BMP, EMF, GIF, ICO, JPG, PNG, SVG, and TIF.
On the usage of image pools, refer to the chapter Image Pool.