The Field Label properties shape the label the appears on a control.

Setting Properties
Viewed in CSS tab

With some additional settings to Alignment, Padding, and Border properties and viewed in Live Preview:

The Style editor lets you easily edit a field label. You can adjust border type, even down to each edge of the border, alter fonts.

Two border styles combined
Ridge style border

Adding Images to a Field Label 

You can use the Style property to add images to labels as a background.

  1. In the Style Editor click the button next to the Background Image URL property.

    The Background Image URL property
  2. Open the image that you want to use as the label background.

    Locate the image
  3. Run the component in Live Preview.

    Loaded image
    You will probably need to adjust the Positioning and Size properties in the Style editor to make the image fit the label size.