Why do I get an error instantiating an interface?

I have a class and an interface, and when I try to instantiate the interface, I get an error:

Cannot create an instance of the abstract class or interface

My code is below:

namespace MyNamespace
{
    public interface IUser
    {
        int Property1 { get; set; }
        string Property2 { get; set; }
        string Property3 { get; set; }
        void GetUser();
    }

    public class User : IUser
    {
        public int Property1 { get; set; }
        public string Property2 { get; set; }
        public string Property3 { get; set; }

        public void GetUser()
        {
           //some logic here...... 
        }

    }
}

When I try to instantiate IUser user = new IUser(); I get an error:

Cannot create an instance of the abstract class or interface

What am I doing wrong here?