Answer
The ressonance structure should look like this:
Work Step by Step
1. Draw all lone pairs that are missing.
As we can see, the nitrogen atom has lone pairs that were not drawed.
2. Identify the lone pair next to the positive charge:
They are marked in the image. "Next" mean that, there is exactly one bond between the lone pair and the atom with positive charge.
3. Draw the arrows:
Follow the same pattern we have learned in the chapter.
(Bring down the lone pair to the bond in the middle.)
4. Do the changes based on the arrows.
* Don't forget the formal charges!