Satan even existing is very dependent on your beliefs, many people claim to want to sell their soul, very few people can say with any conviction that they have succeeded and it is likely that many of those are lying.
There are many ways to go about getting things in life, many that are far simpler than trying to sell your soul.
What in particular did you want to sell your soul for? then maybe we could help you find another, more likely way of achieving it.
To send someone on the website a message you click on their name, which takes you to their profile. Then click on the mail tab, between the "profile" and "photos" tabs.
Satan is an honorific term meaning adversary. It was applied to many biblical beings with individual names through constant translations. Samael, Azazel, etc. were angels with seemingly insidious tasks such as tempting humans to test that they are worthy of going to heaven, or taking the blame for the wrong in the world, hence their names' meanings being Poison of God and Scapegoat of God respectively. Then there's the dragon from revelations which may have actually been called Satan, but again, it still roughly just means enemy. The dragon was an adversary of heaven. As for selling your soul, that just isn't a thing that happens. Spirits have nothing to offer you in this world that you couldn't obtain from them without a bargain of such magnitude. They cannot offer you wealth, or physical alterations, or anything that you might be hoping to trade it for. Not that there's anything in this finite life worth trading eternity for, if that's the sort of system you believe in.
Check this book out
Pacts With the Devil: A Chronicle of Sex, Blasphemy and Liberation
https://www.goodreads.com/book/show/47685.Pacts_With_the_Devil?ac=1&from_search=true&qid=0uhxOf3DbH&rank=5
I'm aware this post is over a year old but I'm still responding to it.
Let's set aside this idea that selling your soul to anybody or anything, let alone Satan, is the worst idea in the world for just a moment. Let's consider for now who Satan is and what he represents.
It's commonly agreed that Satan is the opposition of the Abrahamic God. He was once an angel of God, cast down from heaven due to reasons still debated. In Jewish texts, the Satan was a prosecutor on sinners. To some Christians, he was also known as Lucifer, or the Morning Star. To others, he was always temptation, looming around every corner to promote sin among men to prevent them entry into Heaven. Modern day Satanists view Satan in both a theistic and atheistic light. One of representation of political and social rebellion, the other a deity that can offer power of will and personal freedom than God could ever provide or allow.
The soul itself, can be seen as a spiritual manifestation of one's own life force. That is to say, God breathes life into the body, and therefore the soul is born. If we look back into ancient Biblical texts, we see that in the first book of Genesis, human and animal sacrifice was quite common in those days. Blood was often seen as a life force that could be given to the creator, as to give them life, and in turn, the creator gives them life. It's an endless cycle of give and take. Satan has never been the giver of life, so to "sell you soul" to Satan, is the equivalent to using UK currency in a US shop. It just doesn't work that way.
Satan does not require souls to do anything. The idea of Satan only requires your disdain for arbitrary authority and your willingness to rebel against it over everything else. Satan thrives off of your willingness to put yourself above everything else. Satan represents humanity without a God. To honor Satan is to honor yourself and your humanity.
So if you really want to gain Satan's attention: rebel against God. Question His authority. And stand up for yourself as your own God.