In recent years, researches about the controllable group velocity of light propagation had made many progresses. The mechanism of the generation of slow and fast light, as one of the most important aspects in the research of slow and fast light, had attracted great interest in researchers. In this letter, the authors described a simple experiment for the tracing of light signals in erbium-doped fiber (EDF) at the optical communication wavelength. We have, directly, observed the evolution of slow and fast signals with different waveforms that travel in EDF. Through tracing the wave evolution, when slow light (0