One simplistic way, for say four players, pseudocode:

Create an array of 4 strings
      for n players from 1 to 4
            while keypressed != enter
                  read key and add add to string[n]

for each round
      display string[n]
      n's turn...

That leaves out a million and one features but should get you started. Refer to 'key' and string arrays in the online reference.

Somebody, probably from the same class, had some advance on this topic...
https://forum.processing.org/topic/arrays-in-argument-parameter-would-appreciate-any-help

I downloaded a Library which helped me, But I got the problem where I want a PImage to display which player turn it is. But the problem is when I change the co-ord of the PImage it places another PImage instead of deleting the previous one. I've tried use redraw(); but then my background covers up my other parts of the program.

Hard to help from a generic description like that, but I will give a generic help...
In Processing, in most sketches, you just start draw() with a background() call, and redraw everything in each frame. redraw() is rarely used, actually: draw() is called 60 times per second (by default), so you have to structure your code around this fact...