Lauren, you don't really see the dB in Audacity, you see it later on in Checker.
But we have a handy plug-in which you can download. It calculates you the exact amount you need to amplify or decrease your volume to get to the coveted 89 dB. I use it for all my recordings and my volume is always inside the limits, thanks to ReplayGain. Here's how to download it:
Hope that helpsReplay Gain plugin for Audacity: - http://forum.audacityteam.org/download/file.php?id=4668
1. Save the file to your computer - your desktop or somewhere where you can easily find it.
2. Now browse to the folder in which Audacity is installed. It's probably in C:\Program Files\Audacity) and then open the Plug-Ins folder.
3. Drag the file you saved into the Plug-Ins folder.
4. When next you start up Audacity, you will be able to select the whole recording (Ctrl+A on Windows), then go to Analyze | ReplayGain, and it'll tell you how much to amplify your file to get to about 89 dB.