beginner at unix need help!

[ashmatusunrai]

I have to write a unix shell script, and I've done most of it but I can't figure out one part. I need to write every line containing the word ``delete'' produced by ``man mail'' into a file called ``delete'' and popy every line of a file (in D) called ``dogfile.txt'' that has the word ``dog'' (lower-case letters only) in it into a file (in D) called ``doglines.txt' '. I know how to copy, and I have looked at sort and grepo but I can't figure out how to put it all together. Please help me, I'd be eternally grateful.

[srikpen]

#/bin/bash

man mail | col -b | grep delete > delete.txt
cat dogfile.txt | grep dog | sort | sed -e 's/dog/Dog/' > doglines.txt