I'm thankful you want to learn about Jesus and Christianity. I hope what I say will be only a first step for you, and that you'll continue to grow in your understanding.
A Christian, very simply, is a person who has decided to be a follower of Jesus Christ. As you may know, Jesus lived in the Middle East about 2,000 years ago, and after preaching and teaching for about three years, He was put on trial and executed by His enemies. The Bible (our source of information about Jesus) tells us that three days later He came back to life by the power of God, and was taken up into Heaven. Someday He will return to conquer evil and rule over everything in perfect justice and love.
What sets Jesus apart from every other religious leader or philosopher? Simply this: The Bible says He was God in human flesh—completely man, but also completely God. He came to earth for one reason: to reconcile us to God. Sin had separated us from God, but Jesus (who was without sin) took all our sins upon Himself, and He died in our place.
Why did He do this? The Bible says the reason is because God loves us, and He wants us to be with Him in Heaven forever. It says, "But God demonstrates his own love for us in this: While we were still sinners, Christ died for us" (Romans 5:8). I pray that someday soon you too will become Jesus' follower, by giving your life to Him.