NEVER - NEVER EVER - DID I SAY NEVER!!!
FrontImage = new JLabel(image2);
Variables are ALWAYS starting lower case. Upper case is reserved for object naming.
The problem: If the image isn't big enough, it will not be filling the Label.
Look for "fatcow icons", it's a professional looking, big set (+3500)of icons free to use.
You can include the needed ones directly with your code ( / in resource-folder beside).