its my first time to build an amplifier. i already have schematc diagram. how can i put frquency and volume control on it? i need to put bass, tremble and volume control. thanks.

 

What you want is the baxandall controls for bass and treble - http://sound.westhost.com/dwopa2.htm#baxandall

Volume is simply a potentiometer at the input to the power amp that limits the magnitude of the input signal.

You get better help with more complete information - like the schematic.