In Java, it\'s possible to have methods inside an enum.
Is there such possibility in C# or is it just a string collection and that\'s it?
I tried to override
Nope. You can create a class, then add a bunch of properties to the class to somewhat emulate an enum, but thats not really the same thing.
class MyClass
{
    public string MyString1 { get{ return "one";} }
    public string MyString2 { get{ return "two";} }
    public string MyString3 { get{ return "three";} }
    public void MyMethod()
    {
        // do something.
    }
}
A better pattern would be to put your methods in a class separate from your emum.