This study investigates the stellar life cycle by constructing an Hertzsprung-Russell (H-R) -diagram from observational data. Using both spectroscopy and photometry, the effective temperature and brightness of 50 stars was measured for a diverse sample of various evolutionary stages. The spectroscopic measurements of effective temperature were done by measuring the spectral class of the sample stars. In this part of the research, a telescope and Star Analyser 100-grating was used. The photometric data was gathered with a DSLR camera. Calibration with Vega for all data allowed precise instrument correction and atmospheric extinction adjustment. The resulting diagram clearly shows the main sequence and giant branch, confirming key astrophysical models of stellar evolution.