how to set up my amps

I am not too sure how to set up the gain etc on my amps for my speakers. So can anyone give me some advice on what Gain is and how to set it up etc. SPECS: ALPINE CDA-9885 HeadUnit CEA-2006 Power Rating (4Ohm@14.4 V =1% THD+N), S/N 80dBA (Ref: 1W into 4Ohm): 16W x 4 Max Power Output: 45W x 4 Alpine Type R 6x9 SPR69C RMS Power Output: 100W Peak Power Output: 300W Alpine Type R 5.25 SPR13C Max RMS Power Output: 90W Peak Power Output: 270W Alpine Type R 12" Dual Voice Coil SUB Power Handling Capacity (RMS): 500W Power Handling Capacity (Peak): 1500W Alpine V-Power Mono Power Amplifier (for Subwoofer) MRP-M350 700W x 1 (Max) • 350W x 1 RMS [2 Ω @14.4V (1%THD)] • 200W x 1 RMS [4 Ω @14.4V (1%THD)] • Bass Engine (Variable LP Crossover, Bass EQ) Alpine V-Power 4/3/2 Channel Power Amplifier MRP-F240 - 4/3/2 Channel power amplifier - Built-in Crossover - Blue Power Status LED - 75Wx4 (MAX) - RMS 14.4V Power - 100W x 2 [4Bridged (0.3%THD)] - 50W x 4 RMS [2(0.3%THD)] - 40W x 4 RMS [4(0.08%THD)]