C# :: Populate Data In Datagrid?

im trying to populate a datagrid, i have a datbase class

public static List<Product> LoadProduct()
{
....................
}

i have a product class

gettor & settors
public Product(int id, string Name, double Price, int Quantity)
{
productId = id;
productName = Name;
productUnitPrice = Price;
productQuantity = Quantity;
}

ive added the HTML code to set up the datagrid, which i can see via design tab, but filling it up is harder.

i uderstand it needs a

protected System.Data.SqlClient.SqlDataAdapter sqlDataAdapter1;
sqlDataAdapter1.Fill();// where it require a dataset or datatable
DataGridProduct.DataBind();

as it requires a datatable i converted the list to a datatable when i run it it says null, im not sure where im going wrong, i noe the list works as i tried populating on a table.

public static DataTable ToDataTable<T>(List<T> items)
{
}