Your PID coefficients will depend on many factors of your robot, so we cannot just give you some correct values; you will likely need to do a lot of trial and error to get the behavior you want. There are various threads on our forum that are about PID tuning, for example, you can find some general advice for tuning PID coefficients in Ben’s posts in this thread. Additional information can be found on the PID controller Wikipedia page. In particular, you might consider the Ziegler–Nichols_method.
Additionally, please note that the QTR sensor board in your picture is not one of our products, so we cannot guarantee it will work correctly with our library.
Brandon