I think you need to create the List of customers as a class in it's own right like this
public class Customer
{
public string Name
{
get;
set;
}
public int No
{
get;
set;
}
public Customer()
{
}
}
public class Customers : List<Customer>
{
public Customers()
{
this.Add(new Customer() { Name = "Adam", No = 1 });
}
}
then you can create a Static or Dynamic Resource in your Window and bind to the Resource like this
<Window.Resources>
<local:Customers x:Key="MyCustomers"/>
</Window.Resources>
and create your DataGrid like this
<DataGrid Name="Sampledatagrid" AutoGenerateColumns="True" ItemsSource="{StaticResource MyCustomers}" Margin="0,0,0,106"/>
and then you should be able to see your data straight away even in the designer.
This assumes that you have declared your namespace that the Customer class is in and you have called it local like this
xmlns:local="clr-namespace:yourApplication"
Hope this helps