2003 Spectra Help

Hi I have a few problems my Kia it makes a rattling noise right after I turn it on it goes away only when I have my foot on the gas it seems to be coming from under the passenger's floor. my second problem is I bought $52.00 worth of noise damping material for my trunk because I have a $900.00 sound system in it and the material is stick on 1 side and like rubber on the other and I am not sure what the best way to put it on is. Thanks - JTFX

you all know what sorry I even asked for hlep since no body cares any ways ! :banghead: