This book is aimed at helping those that are interested in learning about some of the analytical methods used for the study of the formation of dark matter structures in the Universe. The development of analytical or semi-numerical methods for the very interesting problem of structure formation is a very active research area. Analytical methods -compared to N-body simulations- are very economical and give more light to the physical mechanisms during the process of formation. In spite of focusing on a very specific problem this book is not self-contained. Cosmological models are briefly discussed, and only flat models with a cosmological constant. The history of the Universe up to the epoch which gravity plays the main role in the evolution is also not discussed. Fortunately, classical books of Cosmology are available for the reader who is interested in these subjects. The emphasis of this book is on specific problems such as the mass growth, the density profiles and the random angular momentum of DMH.