If you begin with a Google search for "InDesign free tutorial layout folded greeting card" without quotes, and similar search phrases, you'll discover many good informative links, free sample templates, and the incredibly rich Internet universe of helpful InDesign resources in which this forum resides.
What a worthless answer. Now that you've written that, searching Google comes up with this thread a top item, and how I came to find this thread. If you have a real solution, post it, if not, keep your keys quiet.