From LinuxSwords Wiki

how to tag mp3-files with id3tool

the usage is very simple:

id3tool [<options>] <filename>
 -t, --set-title=WORD          Sets the title to WORD
 -a, --set-album=WORD          Sets the album to WORD
 -r, --set-artist=WORD         Sets the artist to WORD
 -y, --set-year=YEAR           Sets the year to YEAR [4 digits]
 -n, --set-note=WORD           Sets the note to WORD
 -g, --set-genre=INT           Sets the genre code to INT
 -G, --set-genre-word=WORD     Sets the genre to WORD
 -c, --set-track=INT           Sets the track number to INT

No explaining necessairy. If you want to do it in a for-loop:

for i in `ls *mp3`
do
id3tool --set-album="hello world" --set-title=${i%mp3} --set-track=${i%_-_} ${i}
done

see also lame