That is a standard error caused by trying to access fields from the main() method. You should know to get your code out of the main method. And I think you ought to have two classes. Also you should use the usual conventions about class names; “label” is a name which has already been used, and which ought to have a capital L.
Now you want all your “real” code in the run() method.
Of course, you are making like difficult for yourself, using applets and Swing. Swing classes should be called on the Event Dispatch Thread only. And applets are even more complicated. You will have to go through the Java Tutorials, here, and here. An applet is called within an HTML document, and you usually put the initialisation code in its init() method, rather than the constructor.
Get a FooDemo working with a main method like what I showed you. Then you can try a little Swing thing like what I showed here, last week. Beware: there are two errors in my code. You will find out what they are if you read the whole thread. I have also omitted some of the import declarations.