well see the only way that would happen if you would add a eq to the master channel and you do not want to do that cuz like you said you would be eq'ing the whole mix. its really easy to eq individual instruments im surprised your brother didnt show you that. also you would have to reasearch on google on the frequnices you would have to eq ..an eq chart. yes i was in your situation about 4yrs ago i didnt know anything about mastering but it takes practice i dont expect you to learn over night it took me roughly a year and a half to finally get everything down pact. but keep playing around with it.