1.Part 5.
2.You need to check the first square box: I can read and understand English..., and at the signature area, please put your name, for example, if your name is David Time and your son's name is Tom Time, you can type like this: David Time on behalf of Tom Time.
3. For the area of Print For Your Full Name: you just need to print your full name. You don't need to put your son's name here.