Press the letter keys to type. The arrow things (sprites) change the text size. You currently can't change the position of typing back, up or down (you can only move it right by pressing space). Some of the letters aren't perfectly in the centre. You can type letters inside other letters if you press 2 keys at the same time.
I will try to update it (I might not). Tell me if there are any bugs/glitches in the comments. v1.0.0