New to Java

Hello there,
I am not clear about the difference between a static method and a non-static method. I need to know when I should use one instead of the other. For example, what is the functional difference between the two methods below?

public static void doSomething() 
{
    int i = 1 + 2;
}

public void doSomething() 
{
    int i = 1 + 2;
}

Thanks,

ue_Joe