This walkthrough explains how to request copies of dade county official records

For what it’s worth, walkthrough is common in my programming and gaming circles. Walk-through seems to be preferred elsewhere—there’s a general trend for hyphenated terms to become single words over time, and this is a relatively new example. However, I would only use walk through if I meant it as a prepositional verb, as in “Let’s walk through some examples”. Review seems better to me. I wouldn't use walkthrough because that doesn't suggest the idea of the document changing as a result of the meeting.