GIMP Add border and shadow to a layer

To Add border to layer follow below steps

1. Select the layer then use menu Layer -> Transparency -> Alpha to Selection.
2. Select -> Border Border Selection window will appear. Enter the size of border you want to show.
3. Layer -> Transparency -> Intersect with selection
4. Edit -> Fill with FG/BG Color You need to select required color from FG/BG color panel.
5. Select -> None

With above steps you will be added border to your layer.

To add shadow to layer

1. Select the layer
2. Select -> All
3. Filters -> Light And Shadows -> Drop Shadows
4. Window will appear select/add required values and click on OK