I am trying to improve the audio of some song I have gotten from friends to help them out. For some reason there is I guess hissing in the audio. like the audio was recorded bad, or old recording. something of the sort… anyway I was wondering how to remove the hiss and “Remaster” the audio. can I do this with audacity? (I have 2.0.5 for windows) If you can help me tanks 
Effect > Noise Removal. But hiss is very difficult to remove.
http://manual.audacityteam.org/o/man/noise_removal.html
You won’t be remastering it. The best you can do is reduce the hiss a little. If you go too far in Noise Removal, the background will sound quiet, but the music and voices will start to sound honky and bubbly – like a bad MP3 or cellphone call.
Also, if the show arrives as an MP3, you can’t make another one when you’re done. If you make an MP3 from another MP3, the weird compression sound and damage goes up. You can make a WAV or you can make a very high quality and larger MP3, like 250 or 320 quality. If you need to make a new MP3, you need to install the Audacity “Lame” software.
http://manual.audacityteam.org/o/man/faq_installation_and_plug_ins.html#lame
Koz
thanks man! i will try this
I wondered what it actually did and I think it did really well. (There was also some non instrument clicks in there that i fixed too. i hadnt really heard it because of the hissing thank you for your help 