audacity problem???

hi gang,
ive just done a 71min mix and used audacity to convert it onto my laptop. i checked my recording levels all the way through the mix (and even did a couple of soundchecks),but to me,it sounds a bit of a quiet recording. a mate of mine has done similar mixes using audacity and even has the same mixer,and his have turned out ok!!
do i need to raise the gains more on each channel,or could it be the amp set up im using (its a kenwood stack system)???
also,is there a way i can mess around with the mix ive done using audacity, to make it a louder recording,as i cant be arsed doing it again!!!

any help appreciated peeps!!

i use the mic socket as i havent got a line in socket on my laptop. im sure that the mic volume was all the way up to full though!! help!!

the bars are up nearly hiting the red northern star,but i could allways tweak them a little higher (obviously not so it distorts tho!!).
i think coggledots hit the nail on the head by saying i need an external soundcard, as i use the mic socket instead.

thanks for the info guys. if i get it done right,i'll up it on here and you can give it the once over!!