You are welcome! When you create the giveaway, it will ask for for the giveaway type (step 2). Select "Key." It will then give you a space to enter keys or gift URLS for humble bundle or steam. You can then paste in your gift link. If you are giving less than 50 keys, the system will give you a chance to review the winners before the keys/links are sent. I have successfully given away using this method previously.

If your question is about the humble bundle side, if you claim a bundle, the HB system lets you create a link for each individual game (separate from if you buy the bundle as a gift).

I hope that this helps!