We recommend that you start by reading the SAFE Network Wiki.
You might also be interested in listening to SAFE Network School, a series of podcasts that covers in depth the content of the wiki documentation.
If you want to look deeper, you should have a look at MaidSafe's whitepapers.
Keep in mind that some of the papers are not up-to-date with the current implementation of the network.
Previously, the SAFE Network was being developed in C++.