[Yves]

on that video is using clickable textdraws.

if you new to scripting then you will have no idea how to make that unless you learn pretty fast.

the links will help you.
https://sampwiki.blast.hk/wiki/OnPlayerEnterVehicle
https://sampwiki.blast.hk/wiki/OnDialogResponse
https://sampforum.blast.hk/showthread.php?tid=328267
http://forum.sa-mp.com/forumdisplay.php?f=70

also looking at ******* tutorials on how to script will help you alot.

if you want the dealership script to be like that on the video then you might have to pay if you want someone to do it for you.