Have you considered searching for "Glade tutorial"? I know this sounds obvious but this is literally what anyone answering your question is going to do. There is nothing special to using Glade on a raspberry pi and all the GPIO functions you are using already will still be available.
Also given that Glade is programming language independent, which language do you intend to write your GUI with? C? Python? Ada? Perl?
Electronic and Computer Engineer
Pi Interests: Home Automation, IOT, Python and Tkinter