Warmly welcome to Teragrid project!
To get the basic concepts of Teragrid visit http://teragrid.network. For another introduction targeted for end users but also for developers and others, see here. If you want to get a deeper understanding, start by reading the whitepaper. If you are interested in being a core developer, find a project that interests you, and start contributing to that (maybe pro-bono initially, until maintainers like you and decide to hire you). For Teragrid research and protocol architecture, visit https://github.com/teragrid/teradocs/wiki/TeraLabs. If you are interested in developing Dcodes you can see here, as well as under Dcodes Development (which is also in the sidebar).
For getting started guides, see here