First you need to get a cat harness that fits your cat. If it doesn't and your cat doesn't like the type of harness then the cat will hide it when your not home. Lol
If it's the cat's first time outside and you have a porch thingy then the cat might stay on your porch for a while and you'll just have to sit with your cat, this may go on for a few or more days.
When your cat has found out that outside is safe then she/he will go down the steps on their own. But if your impatient (like I am) then just carry your cat down the steps, she/he may just go back up.
Your cat may sniff the bushes if you have any outside, don't let the cat go in them. To prevent that just shorten the leash by pulling and making it less bungee, then your cat will eventually learn.
Make sure you have no dogs outside. Once my neighbors let there dogs into their yard and then they barked and scared my cat! She ran right into the bushes and I needed my sister to help me get her out
When your cat is used to going outside she/he will go up the stairs on her/his own, and then your cat will go to the door and probably rub against it to let you know your cat wants to go in.
Then as a reward for your cat you can feed your cat after or you can give your cat treats. After doing that for a few days or more than your cat will want to go outside more!
Hope you enjoyed doing this with your cat! That's all you have to do! Have fun!