How to use Blenders GUI? I was making a game with blender like creating buttons and stuff but um... I don't know how to use Blenders API, or GUI. I wanted to create functioning buttons and creating user input on the screen like you would in Tkinter for python. I am really confused on what to do with Blenders GUI stuff... I meanm like how to access and create stuff with it. So is there a way to use Blenders API (mainly I want to have control over blenders GUI to do what ever I want)? 

And when I import blenders game engine like this "import bge" or "from bge import *" but it says model don't exist. What should I do? am I missing a module?
You may be able to learn the Blender interface while working on your game, but I suspect that this is more of a challenge than you need to take on. If you're totally new to Blender, I think you'll find it salutary to gain some familiarity with the Blender and the Blender interface tools by working through one (or both) of two online courses, one by James Chronsiter at [http://www.cdschools.org/Page/455], with video supplements at [http://4chron.home.comcast.net/~4chron/CDCADTutorials.htm], or alternatively Neil Hirsig's course at [http://gryllus.net/Blender/3D.html]. These will give you a solid introduction to the interface, and some introduction to the BGE.

There are also a number of books available that can help, including free downloads from Wikibooks [http://en.wikibooks.org/wiki/Blender_3D:_Noob_to_Pro], and a book by John Blain (a bit out of date, but still using basically the same interface as the current edition), [http://download.blender.org/documentation/pdf/John%20M%20Blain%20-%20An%20Introduction%20To%20Blender%203D%20-%20A%20Book%20For%20Beginners%20%282011%29.pdf]