The analysis of the physical processes between a starburst and its environment requires the complete study of the gaseous component. In this talk I will briefly explain the work I have been doing during my internship at Gemini: the study of the physical properties of star-forming regions in three galaxies: NGC6070, NGC5861, and Tol1924-416. I estimated the electron densities and temperatures, ionic and total chemical abundances, reddening, SFR ,and ionization structure using GMOS/Long-slit data obtained at the Gemini-South Telescope.