Can't access modem with kppp

I installed Woody on a summer 2000 imac about two months ago. Since then I have been trying to get kppp to work. Pon and ppp work fine. I am now running a mixed testing/unstable system with kde3. (Had the same trouble with kde2) dAs far aas I can tell kapp is configured the same as ppp. When

apt-get update

I hate to display my ignorance but I am stumped by a very simple thing. I have woody installed on a new world imac. I want to upgrade to testing or unstable but I cannot find where to indicate the release. I have a 686 machine that I upgraded to unstable and in that version the target release

powerpc sources

I recently installed woody from cd's on a new world imac. I have no /etc/apt/apt.conf file. Should I make one? The only contents of the /etc/apt/sources.list are the cd's and one security address. Can I just add the regular stable, testing and unstable sources or am I restricted to some pow