Writing task 1, please help me?

The flow chart illustrates the main stages to obtain a driving license in US.

Overall, there are six principal steps; in which three exams or tests are needed to pass to enter the next step: an eyesight test, a written exam and a road exam.

In detail, it is necessary to go to the center and fill in the forms first. Then they must take an eyesight test. There is no chance for those who fail this test. Those passing will pay fees to have the written exam. Doing the road exam is the next step for those who pass the exam before. Others, in contrast, must retake the written exam. Those passing will do the road exam too while the failers are allowed to try once more time. Candidates who fail either this third written exam or road exam will pay fees and do all these tests after. By contrast, those passing the road test will successfully get the driving license.