It's an interface, therefore you MUST implement all members - whether you want to, or not.
This error will not go away until you implement the interface in its entirety. You can do what you want within the scope of the method you're implementing, say even raising a
NotImplementedException for instance - but that is your implementation so the compiler is happy.
I won't condone ignorance (you should still learn the hows and whys) but I will offer a tip which may aid in your learning and, if nothing else, future productivity:
From within Visual Studio, when you have the class code file open which is to implement the interface then you can have VS spit out the code for you...
class MyClass : IMyInterface // <- hover mouse and click the drop down that appears
From the drop down you should see the option
Implement Interface 'IMyInterface', click it and voilà! It will automatically generate the skeletal method bodies for you.