How to change content of packet

[Pooja singh]

I want to implement a 5G scenario where I have small base stations(SBS) and macro base stations(MBS) and users. Users request video data and base station reply with the corresponding video file in the packets. 

How should I go about implementing both SBS and MBS? (Do I have to write the whole code like it is in Lena-dual-stripe.cc ?)

and how could I generate packets that would contain content of a video file? 

It would be a great help if I could get some direction as I am new with ns3.

Thanks in advance.

Pooja Singh