Turtle graphics

Import the library and create a turtle. The turtle starts at (0, 0), the centre of the window, facing right (east), with its pen down.
forward(steps) and back(steps) move it. left(degrees) turns anticlockwise and right(degrees) turns clockwise.
import turtle
pen = turtle.Turtle()
pen.pencolor("blue")
for side in range(4):
pen.forward(100)
pen.right(90)
turtle.done()
This draws a blue square with sides of 100 and finishes back at (0, 0), facing right. turtle.done() keeps the window open.

To draw a regular shape with n sides, repeat n times: move forward, then turn by 360 ÷ n degrees (the exterior angle). A triangle turns 120°, a square 90°, a hexagon 60°.
import turtle
pen = turtle.Turtle()
sides = 6
for side in range(sides):
pen.forward(50)
pen.left(360 / sides)
turtle.done()

penup() lifts the pen so the turtle moves without drawing; pendown() puts it back. pencolor() and pensize() change the line.
For a filled shape: fillcolor(), then begin_fill(), draw the shape, then end_fill().
setposition(x, y) moves to a point (it draws a line if the pen is down). setheading(degrees) points the turtle: 0 is right, 90 is up, 180 is left, 270 is down. home() returns to (0, 0).
import turtle
pen = turtle.Turtle()
pen.fillcolor("red")
pen.begin_fill()
for side in range(3):
pen.forward(120)
pen.left(120)
pen.end_fill()
pen.penup()
pen.setposition(-150, 0)
pen.pendown()
turtle.done()

Keep track of the position and the direction. Facing right, forward(80) goes to (80, 0). left(90) now faces up, so forward(30) goes to (80, 30).
x increases to the right and y increases upwards, as on a graph.