The turtle looks like a little triangle in the middle of the screen. The head shows you which direction he is facing. When the turtle moves he draws a line behind him.
You can turn the turtle by telling him to turn RIGHT or LEFT. This pictures shows how to make the turtle turn in different directions. Instead of typing out RIGHT and LEFT I use the smaller words RT and LT, which mean the same thing to the turtle.
To get the turtle to draw a line, just tell him to move FORWARD a number of steps (turtles take small steps, so you
need to tell him to move FORWARD many steps, like 100, to get him to move enough to see). I like to use the
smaller word FD instead of typing FORWARD. Both work the same way.
To get the turtle to draw a shape, like a square, you can give him the instructions he needs to "walk" around the shape of a square.