I am a newbie as well. and I utilize Moodle in this manner - as a Learning Management System.
I can build lessons, tests and quizzes and I can create forums and glossaries.
I can bring in resources or make my own resources and use them within the LMS.
I see Moodle as an LMS - that is - it is a tool to house my content.
But it's not a content generating tool, per se. That would be something like SoftChalk, which Moodle does work with.
Softchalk allows me to build lessons in which I've inserted activites into my lessons (interactive and some flash based).
There are some content (lessons) that Softchalk users have built and they are willing to share them - for you to use or to take and modify, then use. Google Softchalk & Connect.
But every Moodle user (and their content) is not 'linked' to every other, and therefore they are not 'searchable' as you are asking.
There is no general repository of Moodle courses or lessons that I know of, though like you I am still a newbie and may not know of them.