Added the NewControl as a content replacement for the MainWindow.

PcgsInvUi/Views/NewView.axaml

@@ -11,7 +11,7 @@
             <TextBox Grid.Column="1" Grid.Row="0" Margin="5, 5, 10, 5" Text="{Binding PcgsNumber}"/>
             <Label Grid.Column="0" Grid.Row="1" Margin="5, 5, 20, 5" VerticalAlignment="Center" Content="Grade:"/>
             <ComboBox Name="GradeChoices" Grid.Column="1" Grid.Row="1" SelectedIndex="0" Margin="5, 5, 10, 5"
-                      SelectedItem="{Binding Grade}"/>
+                      ItemsSource="{Binding GradesList}" SelectedItem="{Binding Grade}"/>
             <Label Grid.Column="0" Grid.Row="2" Margin="5, 5, 20, 5" VerticalAlignment="Center" Content="Quantity:"/>
             <TextBox Grid.Column="1" Grid.Row="2" Margin="5, 5, 10, 5" Text="{Binding Quantity}"/>
         </Grid>