Questions on spec docs, wireframes, mockups...and where to create them

As a non-tech founder who has to walk developers through the building of a product, I'd like some clarification on the value and need of a spec doc, what should be on it, and should it go before or after creating the wireframes? Also, clarification on the difference between wireframes and mockups would be great as well. What are some places online where I can create all of the above?