Here, you have two options right now, probably more if you keep researching.
The color sensor way:
Which requires you to find the average between the number that the black line represents and the color that the white line represents. Since the light sensor works by detecting how much light is reflected back. Once you are done with that, the you can start inputting numbers.
In my example I am using a greater than to detect anything is greater than my average or reflects the most light which would be white; otherwise is black.
So these two sensors control each wheel, moving one forward when is white and stopping it when is black. So if one wheel stops, the other sensor is on white, thus moving your robot forward when both sensors are detecting white at once.
On the other hand we have @calvc01 way:
This one requires a drive train and a gyro.
Which is aligning yourself with the line and then as you drive through it, you align yourself every so often to make sure you are still centered, and get to your target.
Hey @calvc01, if I am wrong, please correct me.