how do i put a dummy in a car?

i have tried every which way and have had no luck please tell me what i need to do to put a dummy in the car and have some fun. ive just only started in this game and i have no idea what im doing. there isn't much in the way of tips that ive found.

 

It's a mod, by @synsol

 

ok i think i downloaded that mod but how do i use it?

 

got it thank you