You should only need click the 'Share' button at top-right corner of main greenfoot frame and select to export as an application. The executable jar file created will run outside of the greenfoot application.

It might be easiest if you upload the project here on the site, including the source code (checking the 'Publish source code' checkbox). Then we could test its ability to create jar files from it and maybe come up with a solution.

It does not matter where the images come from -- as long as copies of them are placed in the 'images' folder of the project folder. If a wanted image is already on your system, you can use the greenfoot application to import the files by right clicking on the class and selecting 'Set image..' on the drop-down menu; then, click on the 'Import from file...' button and browse your directory to select the appropriate file. You can always either reset the default image for that class or select 'No image' to reset the default after importing the file (which places a copy of the file selected in the 'images' file).

Yes i know i already import new pictures I just forgot to add flappy3.png so thank you for that:) now i when i open jar file is nothing.Before it was just scenario buttons but now its nothing:o i will restart pc maybe this will help.What program do you use for opening jar files?I think i do Java Platform SE binary

You did not check the 'Publish source code' checkbox when uploaded the revised scenario. So, I just copied and renamed one of the other flappybird images. I was able to export and run the project in the form of an "application jar file". I believe I use the same program for opening these files. I am using greenfoot 2.3.0 USB which I have had very little trouble with (hence, not updated to newer version).

When I open with cmd is this thread: Exception in thread "main" java.lang.NullPointerException at java.util.Hashtable.put(Unknown Source) at java.util.Properties.setPropertiy(Unknown Source) at java.lang.System.setProperty(Unknown Source) at greenfoot.export.GreenfootScenarioMain.main(GreenfootScenarioMain.java) a:78)

I hope you are not trying to open the jar file within greenfoot. Just find the created executable jar file for the scenario in your directory and double-click on it to start it.