FFT need help

For the reset, it is a classical reset signal, just set it to 0 at the start up of the system, and then 1.

sink_real and sink_imag is your input signal.

sink_valid is a kind of enable to tell to the FFT that there is signal at its input.

sink_sop/eop is to tell to the FFT when to begin and when to finish, thats corresponds to the begin of your signal and its end. (see Fig 3-4)

sink_ready is set by the FFT to tell you if it can process data or not. It is not useful for streaming architecture (see Fig 3-3), but it is for the buffered ones (see Fig 3-11 and 3-14).

And the source_* are the equivalence of these signals for the output.