<Grid.Resources>
  <c1:CellStyle
    x:Key="redStyle"
    Background="Red"
    Foreground="White"
    FontWeight="Bold"
    HorizontalAlignment="Center" />
  <c1:CellStyle
    x:Key="blueStyle"
    Background="Blue"
    Foreground="White"
    FontStyle="Italic"
    HorizontalAlignment="Center"
    VerticalAlignment="Center" />
</Grid.Resources>
<c1:C1FlexGrid Name="_flex" >
  <c1:C1FlexGrid.Columns>
    <c1:Column
      Header="Hello"
      HeaderCellStyle="{StaticResource redStyle}"
      CellStyle="{StaticResource blueStyle}" />
  </c1:C1FlexGrid.Columns>
  <c1:C1FlexGrid.Rows>
    <c1:Row/>
    <c1:Row/>
  </c1:C1FlexGrid.Rows>
</c1:C1FlexGrid>