Here is an example, as shown in the figure. First fix player 1:
1 chooses C–> 2’s best choice is C (-5>-15),
draw a blue line
1 chooses N–> 2’s best choice is C (0>-1), draw a blue line
Next, fix player 2:
2 chooses C–> 1’s best choice is C (-5>-15), draw a red line
2 chooses N–> 1’s best choice is C (0>-1), draw a red line. This gives the pure-strategy Nash equilibrium (-5,-5)