How do I insert the 307 rear bumper

My friends are getting water from the edge of the bumper's lower vent hole. To do this, I need to insert the bumper to do this.

I guess it works.

Thank you very much, my friend, can I plug in the bumper?

You can do it if you have a little hand. But still it would be better to do it with someone who knows. At least the piece does not increase