ABSTRACT. It is necessary to take into account special factors and methods of interaction between a human and a computer in order to develop a competent and user-friendly multi-user systems. One of the key points is the security of the system and it is necessary to find optimally convenient ways for users to work with it. Only taking into account main aspects and examples of using these methods in practice, it is possible to create a really handy tool for a wide audience. Another important fact is usability, which is the basis for system development. And developing of the system can only be based on practical experience and user preferences. It should also be noted the importance of regular evaluation and analyzing of complete product. Work on improving and optimizing the system should be done systematically.