Real Christians are those who follow the real teachings of Jesus Christ. Jesus Christ gave the good news of the Messenger after him who is called Ahmad. Old bibles have this fact despite changes made many to hide it in other versions of bible.
Islam is the real message from God Almighty which is sent to all human beings. Jesus Christ wants people to follow the message of God. More details can found in many specialised websites. If she has specific questions she is welcome to write.