i won gift how do i redeem it?

Creator has 7 days to give you the game. It will probably show up at won page as a key or link and the giveaway won button will blink when it has been sent.

Go here click button in Key column, redeem key :)
Key will appear after GA creator will add it (send it to you) or creator will send it to you via Steam.
Most important - don't forget to set Received checkbox

Click the trophy with the number on it along the top of the page - it will take you to the page which shows your wins, if the person has sent the key you'll have an option to reveal the key. If you don't see that yet then they haven't sent the key, they'll need to do that manually - they'll have up to 7 days to deliver the key/gift to you but it usually takes a lot less time than that.

If I win a game, when can I expect to receive it?
Giveaway creators are allowed one week to send the gift after their giveaway has ended. Depending on the type of gift and the giveaway creator, you might receive the gift to the email address you have listed on the account page, a key might be added beside the gift you won, or the giveaway creator might have sent you a friend request on Steam to make the exchange. Please remain patient, and do not contact the giveaway creator during this time. If the gift is not received after one week, you can mark the gift as not received, and attempt to contact the giveaway creator on Steam to follow-up.

Read the FAQ. Its all there especially if you are new here. https://www.steamgifts.com/about/faq