[GTLS]

if you mean adding a Checkpoint use:

PHP код:

 SetPlayerCheckpoint(playerid, x,y,z, size); 


or if you mean a Pickup like floating i icon,

PHP код:

 CreatePickup(1239, 1, x,y,z,0); 


then in OnPlayerEnterCheckPoint or OnPlayerPickupPickup add ShowPlayerDialog function to show dilog box.
after that in OnPlayerDialogResponce do what ever you want to do in your list.