Search dmsCookie plugin inside the plugins area of your WordPress website:
or download it from your private area:
... and install it.
Create and customize your script (as descripted at the Step #1 of documentation) and then copy the dmsCookie scrip ID:
... and paste it into the text box at the top of the plugin page!
That's all!
IMPORTANT: Don't forget to modify the third-party scripts as descripted at the Step #3 of documentation.