I think what he meant was how do you use static variables, not how to declare them. But if I'm wrong and you are indeed asking how to declare them, then.
public static int sv;
public static void sm()
You call static variables and method through the class name
MyClass.sv = 90;
There is only one copy of the static variable per class during a single runtime. Hence, it is not attached to any object. Static variables are used as counters for how many objects of a class are dispatched or the common information to be shared among the objects of the same class or the constant of a class such as the PI Math constant.
If this is a school assignment, I hope this helps