To be a follower of Jesus Christ, you must believe Jesus is who He said He is, the Son of God. You must acknowledge your sin (e.g. pride and selfishness) and turn away from it, putting your trust in Jesus to be your Savior, whom you promise to serve as your Lord.
You thankfully acknowledge that Jesus went to the cross in your stead, so that you can have life with God now and forever. You can be assured that this everlasting life exists because of Jesus’ resurrection.
Asking Jesus to be Lord of your life means that you are giving Him control of your life. There’s a popular country song of the past decade with lyrics “Jesus, take the wheel.” This is, in essence, what you're saying when you ask Christ to be Lord of your life.