Firstly just for the record I'ma beginner too! (I've only been doing this for about a year)

you're right that you could just do coordinates so here are your options:

variable method:

action car()
{
var place = 0;
while(1)
{
if(place == 100)
{
//whatever you need it to do here
}
if (place == 350)
{
//whatever you need it to do the second time here
}
wait(1);
}
}

for this option you would have the variable increase whenever the care moves forwards on its route.
(This method will only work if you either have a set route that the person can't stray from
or you want your instructions to appear after a certain amount of movement or time)

position method:

action car()
{
while(1)
{
if (my.x == 100)
if (my.y == 250)
{
//do whatever is needed here
}
}
}

this method is pretty easy but it will take you a while to figure out what coordinates you need
and you'll probably want to do a range so they don't have to hit an exact point.
ie. instead of

if (my.x == 100)

//you would have

if (my.x >= 50)
if(my.x <= 110)

that way they would have to hit some place within those coordinates not one exact pixel.

Alternatively you can do the third method which is distance code and boxes:

have an invisible passable box at your "coordinate" and tell your car if it is within a certain distance from the box do whatever is needed.
This code is a bit more complicated so if you chose this method please tell me and I'll give you the code then.
Keep in mind all this code is untested so you may have to fiddle around with it to make it work perfectly.
The numbers I put are just examples change them to what you need.
hope this helps
rtsgamer706