Blockchain has been with us for a long time, and in many segments of human activities, it has proven to be the technology of the future. Security, elimination of intermediaries, and complete data history fascinate even those who live technology every day. However, the entrenchment of traditional application solutions guarantees that connecting and/or transitioning to new infrastructure will be anything but simple. Taking into account the fact that in the near future, it will become our everyday life, this presentation will present the basic concepts of developing Blockchain applications, smart contracts, and how to connect them with existing application infrastructures.