Here we go,

When melee attacking, you compare st vs. Target defence. It seems it would add 1 black dice per defence following the example in the rules, but it's not clear. Do you compare the two or just add black dice?

By the by had my second session, it's going well as but a few hiccups during fighting.

All vs. Target defence adds one purple die as a base difficulty for all attacks. Then it adds one black die per defence rating of the PC/NPC.
I do not have the books here so I cannot give you page references. I'm not sure but I think this is clarified in the FAQ, check there.