Hey kfglkfgl, first, create the Skidmark images.
Next, create an ImagePoint on your car sprite where you want the Skidmarks to appear.
Now you can easily create your skidmarks by using something like:
If Player is accelerating >>> spawn Skidmark at Imagepoint(1)* at layer
[player layer -1]**
On Skidmark is created >>> Set Skidmark.Angle to Player.Angle ***
*or whatever the number of the image point.
** this is so the skidmark isn't spawned above the player. I suggest create a whole layer specifically to store your skidmarks
***By default your skidmarks are spawned at 0 degrees. If would be weird to have your car going up and spawn a skidmark going right.
Hope this helps!