Christianity is, at its heart, about a relationship with God not about rules and regulations. In fact the history of Israel, on which Christianity is based, shows that a relationship with God cannot be maintained on the basis of rules and regulations.
At the heart of this relationship with God is forgivness and reconcilliation.
God is the one who, not only made everything we see, he also made us and sustains us. He made us for a purpose - to live in relationship with him. Because of this we owe him our allegiance. We should honour him and treat him like God, listening to him and living as he wants us to live.
However, humanity, on the whole, ignores God most of the time. We want to live our lives our own way without reference to him. We rebel against him and don;t want him to tell us what to do. This is what we call sin.
This rebellion makes God angry and leads to a breakdown in our relationship with him. God will punish us and there is nothing we can do about this. So God does something for us instead.
Because of his love for us God sent his Son - Jesus - to show us how to live and ultimately to die for us, in our place, taking the punishment for our rebellion so that we may be forgiven. Those who put their trust (or faith) in Jesus and what he has done are forgiven by God and reconcilled to him.
The heart of Christianity is this renewed relationship through faith in Jesus’ death and resurection.
So you see there are no rules to live by in order to be Christian. Rather I live the Christian life, doing my best to do as God would want me to, because God loves me and has brought me back into relationship with him through his Son.
This is a very short description of what Christianity is about. You can learn more here or ask more questions if you like.