You have to match the signature of the method when you are calling it. Here:
- you should define the return type of the method (
string instead of
void) as already stated in solution 1.
- you defined the method as having a single
string argument, but you do not provide any when you call it.
All these mistakes should generate errors in the IDE anyway, and you should not be able to compile because of them.
There also seems to be an issue with the naming:
seems to represent a class and a collection of objects at the same time.
Maybe you need to get back to c#/OOP 101, and grasp these essential notions?