mkdir /home/you/cs2041/repository
chmod 700 /home/you/cs2041/repository
mkdir /home/you/cs2041/ass2
cd ass2
vi pack.c pack.h lib.c lib.h
cvs import -m 'Initial version' ass2 you start
cd ..
cvs release -d ass2
# ... go and do something else... 
cd /home/you/cs2041/
cvs checkout ass2
cd ass2
# ... make changes to pack.c ...
cvs commit pack.c    # becomes version 1.2
# ... realise later that you messed it up ...
cvs update -p -r 1.1 pack.c
# ... more work and then finished for day ... 
cvs commit pack.c    # becomes version 1.3
cd ..
cvs release -d ass2
# ... etc. etc. etc. ...