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 a lone pair that was 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!
