[Audio~Geek]

Plug your headphones or speakers into your audiobox so you can hear what you're doing.

in your software (cubase LE 4?) make sure the Audio Box USB is the recording and playback device and you are using the ASIO driver.

make a audio track, set the input to audio box input 1 (or left if its called that) record enable (red circle) and monitor enable (speaker icon) when you speak into the mic you should be able to see movement on the meters.
Push the master record and play and start making music.

PS. I'm 100% sure the Audio box and Cubase LE have manuals. That you should be the first place to look for instructions on setting it up.