Now I want to use Skype, but there is no skype package in the list in synaptic. How do I install Skype?
Skype is not in the repository because it's not free software, and its license might not allow repackaging it for a distro... (and even if it allowed, it wouldn't be nice to put it to the repository, because the goal of ALT's Sisyphus repository is to be reproducible, rebuildable from the sources, so that people are able to construct their own distros based on Sisyphus, and then are able to support them, correct errors in them; and non-free software cannot be fixed on your own).
However, there are 3rd-party skype packages prepared for ALT's distros; follow the instructions (sorry that the comments there are in Russian!) at http://www.altlinux.org/Skype#i586 -- as