Meaning: To trace or form (letters, words, or other symbols) on the surface, typically paper, with a pen, pencil, or other instruments; inscribe.
E.g. "She is writing a book."
To write on the board (e.g. whiteboard, blackboard, etc).
Related signs: WRITE DOWN, PUT DOWN, SCRIBBLE, WRITER.
First 100 words.
As you feel more comfortable with the first few hundreds of ASL signs, progress further with your vocabulary and learn signing more.