Can someone tell me that how can I make a thin black margin around an entire island what contain all bonuses and territories?

Try selecting all of the territories on the edge of your island.
Then press the following keys: CTRL+D (duplicates them), CTRL+SHIFT+0 (makes them slightly bigger, press multiple times if you want to make the margin bigger), END (puts them at the background, if you already have a background press PAGE UP a few times until it shows up). Then set the colour to black and the line to non-existent. That should do the trick.

ctrl+shift+0 dont make here nothing :\

You mean the outset option?

with inscape: select the territories you want, copy them same location, union them then outset

That's exactly what I said, but with the shortkeys. Urfang, do you have an AZERTY keyboard or something? Because it works with me.