Well, I'm from the country where Orthodox Christianity is a primary religion, so I'm obviously familiar with it, but more from the cultural and historical side, especially since I've spent considerable time in the past studying Byzantine iconography and symbolism.
As for the websites, I see there are many in English, but since I haven't explored them, I can't really recommend a good one. I'd suggest a good old fashioned research in a library. There's a better chance that some university library has some works by Church Fathers, for example. That is if such library is at your reach.
So, I don't know if you're interested in Orthodoxy from scholarly side or to practice it. But, either way,
Early Church Fathers, with the emphasis on Eastern ones, are the beginning, whether you approach it from historical and philosophical side or from theological side. (being familiar with the Bible and New Testament goes without saying). I'll just mention some names, but I can't really remember their works, 'cause I mainly used them as references and *watched their faces on infinite mosaic and fresco programs*, but I'm sure you're gonna manage
:
Origen, Athanasius of Alexandria, Clement of Alexandria, John Chrysostom, Basil the Great, Gregory of Nyssa etc. Then you have
Byzantine theology:
Maximus the Confessor, Pseudo-Dionysius the Areopagite, John of Damascus, Symeon the New Theologian, Gregory Palamas etc.
So, I have no idea if you can find English translation of their works, but now you know what you're looking for, at least. It must be something translated. The best bet is Gregory Palamas, cause he kind of became fashionable in the West, or so I've heard. That's probably because of Hesychasm, a form of deep prayer, contemplation, almost like a meditation. And we all know how fashionable meditation is.
Well, I hope this somewhat helps.