Inheritance

Could anyone please let me know how I would go about adding a variable into a collection or class that is part of an inherited class

EG: I would like to add a value into the columns collection in the DataGridView.

class MyGrid : DataGridView
{
private String ColumnStyle;
public MyGrid()
{
if (this.Columns.MyDisplayStyle == "Decimal")
{
// My code here
}
}
}

The reason I want to do this is so that I can see if the column needs me to display it in a different way.

Thanks