Hi Frank, i link you an help i done when i programmed the GG Basic.
There is also a sample with the input field in the online list.
Anyway....
Look Here
This is the correct mode:
//Input(x, y, width, font_size, input_var)
$var = "";
Input(100, 100, 250, 24, $var)
In your case you need to use Print and after Input.
After all use Render() to show.
I'm happy you are using it, i will update it soon for iOS 6 / iOS7
If you have some functions to suggest please don't hesitate.