How to put a circle ON TOP of a python tkinter window grid and be able to change its position

Question

Hi i'm making a game using a 7x7 grid for a school project however I'm struggling to put a circle (for the players and computer token) on top of the grid in each box and be able to move it to different locations of the box. this iis my whole code which I have done so far:

import tkinter as tk

                
        #this is not working (below)
    def create_player():
        #print('Create_player')
        #Canvas.create_oval(1, 1, 1, 1, outline="purple", fill="yellow", width=2)
    # error msg : "name 'Canvas' is not defined"

create_player()

When it is run it displays a tkinter window displaying two buttons saying 'Start' and 'EXIT'. (ive cut this out)

When 'Start' is pressed the window closes and opens a new window with an orange and green 7x7 grid with a yellow back ground, the error is shown on line 292 I have written the error underneath it. What I am planning to do is to put the circle on the bottom left box and move it across a number of spaces (from when I roll the in game dice (havent made yet) ) and every eight spaces it goes up instead of across and changes its direction...(also cut this out)

I need a circle to go on top of the grid and move about ...

I know how to do the dice btw

Here is full code on GitHub: https://github.com/KoolOllie2002/summer_coding_project_7x7_grid

Thanks for your help!!!