windows 10:
hold windows key and press +
a menu will show up
find the emoji you want by typing íts name directly at your callsign box
once you found it, click on it
see the box at the top left with an arrow pointing right with your emoji in it? click the arrow to type that emoji
windows 8.1 (i guess) or lower
search the emoji on google
copy it
paste it in CIU
done