czym instrumental of both of these? or do i just ignore the first one?
yes, got a little boobo here. The second one would be a correct definition. By mentioning "co" I meant that you can use "czym" instead of "co". The situation to decide when to use it depends in most cases on whether the verb is reflexive in Polish or not. The overlap in Polish vs. English in this respect is not 100%.
For instance:
Czym się martwisz/What are you worried about (relfexive in Polish, therefore "czym" is correct, but not reflexive in Enlish)
This is pretty much all I can say about that. The rest is a question of remembering which verb is, or isn't, reflexive in the Polish language and then using "czym" in a given context.
EDIT:
The example above contains the verb "matwić się". But there is also a nonreflexive form as in "martwisz mnie" (you're worrying me/I'm worried about you).