Let us assume you have in your possession a textbook of English As Second Language that came with an audio tapes. You are assigned to memorize a passage of 30 sentences long from the book and the same passage can be found on one of the audio tapes that came with it.
To record the audio clip:
Go to the directory where foreign language audio sentences are to be saved to, e.g. /data/English/Segment12/English
Configure your sound card to record from the audio tape deck.
I use record sound recording utility. It is terminal-based and very light. I want all my clips to be sequentially numbered from 1 to 30 and have the same prefix:
% record -o en12_
Hit the space bar to start recording, and Play button on your audio tape deck to start playing the segment.
At the end of the sound clip, hit the space bar again and exit from record with 'q'. What you have now is a 16-bit stereo WAV file saved under the name en12_.wav