Which link? The compressor? The compressor is found under Effects → Volume and Compression. You may also want to try the Limiter which is a fast kind of dynamic compression. The limiter is easier to use with fewer settings and you are less likely to get side effects.
I’m trying to edit an online call for a podcast. The person I was talking with had something going on with his mic where the volume kept changing abruptly, as if he had a short in a wire or something. I’m playing around with Compression and Loudness Normalization in Audacity, but there doesn’t seem to be any way to really smooth it out. Any ideas?