New here how does this site work exactly?

https://www.steamgifts.com/about/faq
https://www.steamgifts.com/about/guidelines

Welcome to Steamgifts. Keep your arms and legs inside the vehicle at all times as some members to tent to bite. Lugum, I'm looking at you. He has a tendency to bite.

Also no talking, no smoking and crying babies must be deposited in the receptacle in the lobby. Thank you, the Management.

Aside from that you can enter for the specific giveaways so long as you have point, are the level listed and/or are in a group, whitelist and are in said region. Plus it can take some time before winning any that you enter. Not everyone wins on their first day. so please have patience.

When making a giveaway, you must be able to provide said game in order to avoid getting reported. This site will not provide the games you want to give away. Also you can not give games that are already in your own library unless you have a spare. Also when gifting a gake from steam you have to see about regional pricing.

Other than all that, welcome and enjoy the ride.

A while after reading the FAQ above, you might want to delve into the evolution of SG by reading the announcements.

Also if you plan to make giveaway with a game bought at humble bundle bundle or store - use generated key instead of gift link. HB treats steamgifts as trading site and can ban your account if you will tell them (for example in question to their support) that you use steamgifts.
So remember - keep it a secret from humble bundle if you are using their keys here xD

I'm not sure what you mean when you ask "do they send the code to your email". Users on this site buy games with their own money and then create giveaways here to basically raffle the game off. All users here get a certain number of points to spend and they use them to enter whatever giveaways they want. If you are the winner, the giveaway creator will send you the game. The giveaway creator can add a key directly to the site when they create the giveaway and send it to you through this site or they have the option to email you or add you on Steam if they want to send it that way. The vast majority of users buy keys from sites like Humble, Fanatical or Indie Gala and send them to the winner directly through the site. It used to be common to buy games directly from Steam, but that is much more difficult now since they do not let you store games in your inventory and there are a lot of restriction on what regions you can send games to depending on how much the game costs in the regions sending and receiving the game.

Go away,It's a trap, I have been on this site for 7 years

First you need to sacrifice a lamb during a full red moon and then "they" will reach through your mail.
Welcome to SG.

Welcome to Steamgifts! I hope you enjoy it here!