Can I create a GIveaway if i have only the key?

For coupons I mean Steam Gift (I follow the Guide http://www.steamgifts.com/forum/X8ct9/the-new-gifters-guide-to-gifting)

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When you purchase a new game, you can either Purchase for yourself, or purchase as a gift.
"Purchase for myself" puts the game in your library.
"Purchase as a gift" gives you these options to either send it immediately, or store it in your inventory to send later.
You should select Store the gift in my inventory to send later.
)

Then it's ok the way of guide and if I have a key, right?

Yes, i mean a copy in my inventory. Thanks!