adb shell mount sdcard
adb push "file name" /sdcard/
It's easiest if the rom zip is in the same directory as the ADB you're using. Otherwise you have to mess with paths instead of just typing the file name. Also, don't forget .zip at the end of the file name. As for the link, here you go.
Flashing LG signed Firmware - LG Spectrum - RootzWiki