JSON POST API - Dynamically change variables within the body & also repeat post for x times

Hello all! i’m somewhat new to postman, so this is perhaps quite a nooby question!
So i’m learning postman in my own time and the forum’s been really great help but I want to understand the concept of the ‘tests’ functionality.

So, in my example I have a POST API (JSON format), it has a body which has lots of variables but there is only 3 x specific variables of which I want to dynamically change, with each ‘post’.

I found this link which talks about a very similar thing but it eludes me in terms of understanding;

Basically, I have var1, which I want to increase by +1 every time I run the script, for a max of 10 times (i declared a ‘count’ var in my environment for 10, so to run 10 times).

I’ve managed to attain and in turn, make the below TEST script - but I don’t know if it’s right.

var currentCount = pm.environment.get("count")
var var1count= pm.environment.get("var1")
if (currentCount > 0){
currentCount = currentCount -1 ;
var1count = var1+1 ;
pm.environment.set("count", currentCount);
pm.environment.set("var1count", var1);

Also, when I try to declare the var1 within the body, it doesn’t seem to work. It looks like below;


Now I don’t know if i’m being silly here - but am I on the right track? and what am I doing wrong?

1.) Is it right that the body of my POST can be dynamically altered and i am declaring the variable correct?
2.) Does my test script do me justice? and is it even right?