Can someone explain the Holy Trinity to me?

[Teuthida]

I never really got this and even went so far as to take a history of religion course to try to understand it. Still confused. Is Jesus part of God, or is God Jesus, or his son (whatever that means in terms of an omnipotent being having a human offspring) and if God is all powerful why did a human have to die to undo the original sin instead of just doing away with it with a snap of a metaphysical finger, and what exactly is the Holy Ghost/Spirit besides a nice little birdy in all those annunciation paintings? And why do people pray to Jesus if he was a human even if he could do nice tricks/miracles? Isn't that almost like idol worship? And if Jesus is God then why pray to them separately? And again...where does this Holy Spirit go? And since one prays to God, Jesus, the Holy Spirit, Mary, and who knows how many saints, doesn't that make Christianity a polytheistic religion?

Hmm, that's a bit confusing and run-on-ish but yeah...