Equalizer application how to start

How can i begin this application ?

Any Idea

In an equalizer application, the signal is decomposed into its Fourier components (via Fourier transform) then the bandwidth of the signal is divided into multiple small bandwidths. Then each of these bandwidth are multiplied by a custom gain then the whole thing is returned back via inverse Fourier transform.

do your readings on how equalizers operate and function. Then, develop a simple equalizer that opens a signal (via browse button) and change the gain of its different bandwidths via sliders and show the output. You should compare your output with the output of any available equalizer online. i.e. download an equalizer, feed it with the same signal and compare the output with your output. The two equalizers should have similar output ?