A statement like "board = 5;" needs to be inside a method; you've put it in the class body, where statements are illegal syntax. All you can put in a class body are variable declarations, with or without initializers.
You might want to put your assignment statement into a constructor for this class.
You're welcome. If you ever teach Java to students, you learn to look for this mistake fast. The other similar one is declaring a local variable "public" (for example.) The error message also makes no sense and it's very hard to see what's wrong!