I agree with Flimzy. But let me analyse the question from a different perspective: The point is not about the quality itself of the question, since this is totally independent of being "off topic".
I'll explain better: A question can be a great question even being off topic.
Off topic and quality are not two dependent features. With this, I'm not saying that your question is bad or that it should be down-voted. Not at all, I'm just saying that it doesn't fit here.
If we allow a question "Spanish to English", then we should allow any similar question to any language, and, theoretically, on any site. I could ask on EL&U to translate a figure of speech from "English to Italian", but that would be certainly off topic.
On the contrary asking "X Language to Spanish" is totally different. You talk about "having knowledge in both languages" and it would make sense (it does), but on EL&U there are many native speakers, not just English, they even asked questions for languages like Russian, and Spanish is a much more spread language than Russian.
Edit: Check the Meta discussion about this issue on the French SE site.