Hi there,
Thanks for the kind inquiry! Jav-It is primarily a command line interface tool, so you will need some knowledge about command line interfaces to get the most out of it (that's why double clicking it does not launch anything). That being said, the GUI is just fine for getting people introduced to the simplest options. The reason why your getting graphical glitches is because your computer is likely running on a non-English locale. To fix this, simply perform the following:
1. Open the jav-it_gui.bat file in a text editor (eg Notepad++ ).
2. Create a new line at line 1 and add the line "chcp 65001" to it.
3. Save the file and run again by double clicking it.
After this, your terminal window should display the GUI correctly.