Flash 8 Racing game question Part2: AI characters running along a field?

There are two parts to this question actually, but the first one isnt AI related so its in the Flash 8 section of the forum. Baisically, the game is a track on a field where racers run to the finish line. Two of the characters will be computer AI and run automatically to the end.

This is question 2: How exactly do i make these other two characters run by themselves in a particular direction. I just want them to run straight for the end of the track but i dont know where to begin. Can anyone help me?

Here is a basic image of the game so far. The character at the top and bottom will be AI