How to use MessageBox in class library?

Here is my code

```
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace MessageBoxes
{
    class ShowInfo
    {
        MessageBox.Show("test");
    }
}

```

i can load MessageBox but can't have show property, MessageBox.Show("test"); <-- fail