In repl.it, scroll down to Practical and choose Python (with Turtle).
Documentation for Python turtle graphics
Useful Settings in Python Turtle
Try this code. Play around with it some today.
import turtle # allows us to use the turtles library
wn = turtle.Screen() # creates a graphics window
alex = turtle.Turtle() # create a turtle named alex
alex.forward(150) # tell alex to move forward by 150 units
alex.left(90) # turn by 90 degrees