If the barcode programs are in the debian repositories, and if you have done a hdinstall. All you need to do (as root) is apt-get install programx. You can do apt-get -s install programx to simulate what changes will be made to your system if you install this program (nice). If they aren't in the debian repositories, they still might be provided in the form of .debs from the author's website. Try using dpkg to install if that is the case. If you do a hdinstall and need add new programs (or update) you will soon be singing the praises of apt-get.