It's been 3 or 4 hours I've been searching for it.
This is my command:
convert -gravity center -size 500x500 -background '#263238' -fill white -font "IRANSans.ttf" -pointsize 32 pango:"<span face='IRANSans' foreground='white'>درود</span>" bge.png
But I want to put this text in the middle of the picture. Same thing that this line does in CSS: