This report presents an EEG-based brain-computer interface (BCI) in which subjects could select a picture from a set on a computer screen. The application is centred on detecting steady-state visual evoked potentials (SSVEP) in EEG signals recorded on the scalp of the subject. BCI2000 software platform is used in this project as a basis for the whole system. The platform will link its modules and the developed ones needed to achieve the closed-loop BCI system. In this context, a C++ computer application with 16 targets and a MATLAB signal processing module were then implemented using the proposed method. In offline tests for a set of frequencies with differences of amplitude up to 15 dB, detection was achieved. Detection was also achieved in online tests.