The sign for "write" uses a quick scribbling movement across
the palm of the left hand.
The tip of the index finger is touching the dip of the thumb.
This sign can also be done using a "downward" writing movement
instead of a sideward movement. The non-dominant hand does not move.
You could use a quick, downward movement of the dominant hand to sign write
as in, "I wrote a paper."
Or you could use a couple of repeated movements.
Sample sentence: Do you like to write research papers?
However, if you wanted to sign "write your name" you would use a
sideward movement and do it a bit more carefully.