I would caution you to gather more than one source. The Roman Catholics have their own version of history which I would deem spiritually dangerous; historically inaccurate and misleading. And you could probably add a few other denominations to that as well, it's just that Roman Catholics had centuries of revision under their belts along with many reasons to demonize people still going on to this day. Mind you, they've also controlled education in much of Europe over the centuries.
Controlling education does not mean being truthful, if you can catch that in what I'm saying.
I find Bible Encyclopedias helpful as well. They might go beyond the New Testament (the Christian church), but that can help fashion for you some background as to why some denominations formed.