The main goal of this book is to break down the huge barrier of difficulties faced by  beginners from many fields (Engineering, Physics, Chemistry, Biology, Medicine, Material Science, ...etc) in using X-rays as an analytical tool in their research. Besides fundamental concepts, MatLab routines are provided, showing how to test and implement the concepts. The major difficult in analyzing materials by X-rays is that it strongly depends on simulation softwares. This book teaches the users on how to construct a library of routines to simulate scattering and diffraction by almost any kind of samples. It provides to a PhD student the knowledge that would take more than 20 years to acquire by working on X-rays and relying on the available textbooks.