How to manipulate incoming packets ?

[sa3er]

When i see example.com , he send a lots of packets to my machine that each one contain many things such as:

<script type="text/javascript" src="https://www.example.com/3fr43r45tff4gh3.js"></script>

But i want know that how we can manage & manipulate incoming packets to for example :

<script type="text/javascript" src="https://www.example.com/happy_new_year.js"></script>

Do you know anyway?

PS: I found Burp Suite that claim to packet editing but i don't know how its work ....