This chapter introduces neuroimaging researchers to the concepts and techniques of diffusion magnetic resonance imaging data processing. Using the freely available ExploreDTI software, we provide a step-by-step guide for processing multi-shell High Angular Resolution Diffusion Imaging data and generating tractography based on constrained deconvolution. Brief explanations of the rationale behind each processing step are provided to aid the researcher in understanding the concepts and principles involved. Potential processing pitfalls will be discussed, and tips for troubleshooting common issues will be provided. An additional step-by-step guide for processing DTI data using the open-access AOMIC data set is also provided, demonstrating command-line that can also be applied to process other large neuroimaging datasets.