To draw arrows in GIMP, here is what you can do.
- You can find a plugin at http://registry.gimp.org/node/20269
- Download the .scm file (arrow.scm)
- Save the file in the scripts folder of GIMP
- e.g. In Ubuntu open your home folder, press ctrl+h to show hidden files, open .gimp-2.6/scripts
- Open GIMP
- Using Tools->Paths draw a path. i.e. click two points
- Next, go to Tools->Arrow and press OK
Cheers!