assign content fieldValue to asp element

Hi,

I have created I custom Page Layout where the Editor can choose a Color in the WebPart. The Color is saved in a Content FieldValue:

TextField tf = content.FindControl("Background") as TextField;
tf.Text = lbColors.SelectedItem.ToString();

When I look into the Library to the Background Field, the selected Color is saved there. Now I want to add this Color/value as the Background Color for the Webpart in asp:

<WebPartPages:WebPartZone ID="Top" runat="server" FrameType="TitleBarOnly"  Title="WebPart"  BackColor="HERE I NEED THE SAVED VALUE"/>

Thanks and the best regards

Darkman