Main goal of this dissertation is to explain the importance of business planning. Furthermore, this dissertation explains the importance of small and medium enterprises and what is necessary for successful business venture. Among all that, the first part of this dissertation explains the difference between business idea and business opportunity and how to avoid most common mistakes during implementation from idea into opportunity with help of business planning. Didactic playroom is a place where children can spent their time quality. To their costumers it provide safe, quality and professional short-term service of guarding kids while they learn during games in an adequate place. Entrepreneurship team, that has two members, Ivana Marić and Ivona Martinović, has recognized business opportunity to open didactic playroom in centre of city Osijek. This dissertation describes implementation of learned curriculum from course Starting business venture through writing business plan that consists description of business, description of investments, analysis of market justification and analysis of financial elements of business venture. After research and processed results, conclusion of profitability of business idea was made.