First time trying to record music cassette using audacity tape deck. When attempted “start monitoring” heard only loud continuous echoing noise. Never recorded anything. What is that noise and how do I get rid of it in order to record the cassette? 
Audacity doesn’t make tape decks, so you probably got Audacity with a deck made by somebody else. You can get feedback if you’re trying to record your laptop microphone instead of the deck. What did the instructions say to do to connect the desk to your computer and what kind of computer is it?
Koz
This set of tutorials should help you: http://manual.audacityteam.org/o/man/tutorial_copying_tapes_lps_or_minidiscs_to_cd.html
WC
The tape player was received with Audacity software disc. The disc was chewed up by my dog (yes, i can hear the laughing) so I downloaded audacity from the internet and connected the simple tape cassette player via connection cable supplied - i.e. one end is a usb port coonection for my hp laptop the other end is small plug in (as for cel phones, nook books, etc) for the tape plater.
For a USB cassette player it’s pretty much the same as a USB turntable. See here: http://manual.audacityteam.org/o/man/recording_with_usb_turntables.html
Actually you’re probably better off - as I’m guessing that they will have shipped you an older version of Audacity. The latest version is 2.0.2 (and watch out for 2.0.3 in the next few days) .
WC
Was he tired of eating your homework? My sister has a cat that eats cardboard boxes. Literally. She turns them into dust.
Koz