Make a GUI similar to arduino with added features

I am new to this whole GUI making. And I want to build a GUI similar to arduino sketch having the same libraries and same compilers and having the ability to program an arduino board through the selected serial port.
I am making the style sheets in the qt designer and as it is the graphical part. I am able to cope with it. But I am not familiar to the coding involved to link the serial port and workspace and the compilers. So where do I start so that I can gain the whole knowledge of it. And for the record I want to code it in python as it is easy to play with the classes and objects in python.