Hi Loofon and Welcome to the forum, you might want to have a look at the following FAQ which explain where everything is
Welcome to Benefits and Work Please also read
this topic The phone call will capture details to ensure the basic eligibility criteria have been met. This can be done in paper but it seems easier for most people to make the phone call. Our PIP guides explain the process and what questions you will be asked, so you can have that information to hand.
The call will then trigger the despatch of the PIP2 form (or booklet) that must be completed in detail. The PIP guides explain this too.
PIP help for claimants The requirements of PIP are very different from PIP and the change was with the express intention of saving money. Our guides aim to give you the best opportunity of explaining your situation in terms which the DWP understand and which match the language used in the descriptors.
I suggest that you have a good look at the guides, then reply to this message if you have any specific questions. You will find it easily in future if you bookmark/favourite it on your web browser now