MusicMatch and the recorder component should already be open. Type in the name of the first song you intend to record in the field provided, then single-click on the name. Make sure the tape is already cued up on your tape deck at the point where you want to begin recording. Use headphones or an old walkman to do this if your tape deck has already been disconnected from the rest of your stereo system. Get ready to do two things at the same time.
Press stop on the tape deck too.
If you don't, the program won't know that the song is over and will keep recording the mp3 file. On recent versions of MusicMatch, there a function which can detect pauses on the sound source, but I am not sure if it will work with a hissy tape. The current freeware version of MusicMatch doesn't seem to have a way to adjust recording levels, and just takes the levels straight from the original tape. You can raise or lower volume on playback using the slider on the MusicMatch main component, but if the levels were low to start with, this won't help much.