Just my 2 cents and method of installing a Rom when I had a D2: backup apps/system with titanium backup, and then open the bootstrapper, hit the top option; I think its called bootstrap recovery. Then hit reboot recovery. Once you're booted in make a nandroid, wipe data/factory reset and go to advanced and wipe the dalvik cache as well then install the Rom. It's been a while so I'm not sure if you actually have to install cwm using Rom manager first.
Also, a few things to keep in mind:
When installing the .zip (the Rom) do not choose update.zip. choose a zip from your sd card. Once youre in recovery that'll make sense.
Make sure the file size of the Rom matches the advertised size. You can use a file manager to do this. The reason I say that is because I ended up with half of a Rom that eventually bricked me because it wasn't the full file.
I know this can all be overwhelming at first but I promise its A LOT easier and simple than it sounds.
Sent from my HTC Rezound.
Rooted, unlocked, and ready to rock!