ANimation with Turbo C

My question is how do I process cars simultaneously? i.e I want to use something like multi threading but don't know how to implement it in Turbo C.
I will present what I did till now.

|------|
_______________________| 1 | 2 | 3 |_____________________
Car1 arrives--> Car1 moves ahead-->
___________________________________________________________________

1, 2, and 3 are the three slots where cars wait. Slot 3 is the place where the car actually gets serviced.

This is what I have done now--> Works fine
Car1 arrives at service center.
Car1 knows that slot 3 is empty so goes for servicing.
Car1 once serviced moves ahead
Car2 then arrives, goes to slot 3 gets serviced and moves ahead. Same holds for other cars too.

I want to implement --> DONT know how??

BEFORE
|--------|
___________________ ____| 1 | 2 | Car1 |_____________________
Car2 arrives -->
___________________________________________________________________

AFTER
|--------|
___________________ ____| 1 | Car2 | Car1 |_____________________
Car3 arrives --> Car1 is "Serviced." moves ahead
___________________________________________________________________
so on...

Car1 arrives at service center.
Car1 knows that slot 3 is empty so goes for servicing.
Car2 follows Car1 to arrive at service center.
Car2 checks if slot 3 is empty.
Car2 is queued int slot 2.
Car1 has finished servicing, moves ahead the road.
Car2 replaces Car1 to get serviced. If there are other cars following Car2, they all should wait.
Car2 has finished servicing, moves, replaced by the other car behind it if any. and so on...

My question is once car1 starts and goes to slot3, how do I start other cars simultaneously?
My present algorithm is something like the following:

int main()
{
int i = 0;
while( i<3 )
{
Car1(); //moves the car
i++;
}
}

Car1()
{
while( x < xmax )
{
if( car is at slot 3 )
delay();
//... update screen for animation and move the car
}
}

I hope I'm clear...