Hi Waheeda
Welcome to the forum, you might want to have a look at the following FAQ which explains where everything is
Welcome to Benefits and Work In case you are not aware, your real name appears to be showing in the forum, if you want to change this then follow the instructions in the following FAQ
My full name is showing, how can I stop it?
No, you don't have to write on the PIP form. You will need to put your son's name, national insurance number, and a page number on each page that you send in.
Make sure you put the question clearly - so they know which you're talking about. When I've done this I tend to go back to the form and in each question box I write "see page X,"
BIS