Help the new guy

Last week bought HTC one x, my first ever android phone. I was using iphones, since the 3G.

I want to flash the ROM (that's what it is called, right?) Because I am frustrated with all the AT&T crapware. Unfortunately I cannot find any good tutorial which tells me everything from how to root, to installing a custom rom. And yes, CleanRom 4.1 or cyanogenmod 9 alpha?