Draw offset to the border of object

[orxshi]

I am trying to draw an offset border (red in the figure) around an object shown in the figure. The offset border should have the same profile as the object. I tried selecting object, creating a border, scaling it however, I couldn't manage to get what I want. Would you help please?

[PixLab]

Your png is transparent, so quite easy,
Right click on it in the layer dock, select "Alpha to selection", then go to Menu > Select > Grow > input the number of pixels you want to grow
then from here quick 2 methods

1) you don't care if the tail is rounded: So go to Edit > Stroke Selection (input the thickness and so... Be careful it will use the foreground color (FG-BG are the 2 square just below the tools box)

2) You would like the tail more of the shape of the draw: don't do number 1), instead go to > Select > Save to Path, Then Select > None, Then go to the path tab (near the Layer tab), click on the "eye" to show the path (same principle as layers) Then select the path tool in the tools box, and re-shape the tail
Once you did it, and are happy with the shape go to Menu > Edit > Stroke the path

EDIT: better to stroke with a brush ("Stroke with a Paint Tool", then click to chose), not like I did (screenshot, with a brush it's smoother, prepare the size of the brush before to stroke)

   

   

   

[orxshi]

This is exactly what I wanted. Thank you very much.