no worries… see if this helps! 
lifted from the FAQ:
- Steam keys? How do they work?
When you get to your Humble Bundle download page, you should see 3 ways of getting the game: by downloading a zip file, by downloading an installer, and by getting a steam key. This way, you can have the game both on steam and on your local hard drive, if you want! To use your steam key, grab it from your HB download page and:
- Open Steam.
- From the menu, select “Games” → “Activate a Product on Steam…”
- Click “NEXT” until it asks you to enter a Product Code.
- Copy/paste the Product Code / Key into the text box and click “NEXT”.
- Steam will confirm the product code by indicating that you have access to “Steam Sub 30994” (the Stonehearth Alpha).