Engine doesn't start, only clicks...

[bunskippy]

hmm, newbie question here: how do I know if I have a engine-chassis ground or not? Obviously this all used to work, but hasn't recently.
I got the battery charged and replaced the negative cable (screw was rusted through and broken in there). There are some deposits on the positive cable, but the battery is connecting (interior lights come on, headlamps as well.) Am I right to think that b/c there is a connection, it's not the cable's fault, or could there be a connection but of limited strength to allow the full amps necessary through?

<edit> just went out and tried to jump the battery using my 2002 CR-V. After the Pos terminals were connected I connected the cable from the Neg on the good battery to a cross-beam in my Pony's engine compartment. It sparked so I disconnected. Re-read the directions which said attach it to the engine block. Did that, it sparked. Now turning the ignition key does nothing -- no more clicking even. Any advice? Did I toast something inadvertently?