What modules are you trying to install? It is possible they are not packaged by Activestate so they won't be found in the default repositories. There are a couple of third-party repositories that have more modules. What commands did you use?
in reply to Installing modules
What zip files did you download? I am guessing you got the pre-built binaries from ActiveState. It is better to install those through PPM. If you also get the .ppd file, you can do a command-line ppm install. But if you downloaded them, then this means they exist in the repository and should be found through PPM.