A graphical user interface of the program package ERA-DD for the input and editing of initial data for a two-dimensional boundary value problem is described. The boundary of calculation domain is approximated by pieces of straight lines and circle arches. The input of the information about the boundary is provided graphically and numerically. A special quasi-structured grid is constructed in order to solve the boundary value problem using a domain decomposition method without overlapping of subdomains. The algorithm of constructing the quasi-structured grid is proposed. The input of the information about the problem can be carried out by means of the Wizard dialog.