Knowing is Growing! (Knowing about Islam)

If knowing is growing then i want to be big and tall! Since we are going into the chapter about Islamics, i want to learn more about it. One thing i really want to know is about Islam. i heard that Islam, Hebrew, and Christianity come from the same origin, yet have different beliefs. when i tried to ask how that could be, my dad fell asleep. Later i heard it was Muslim, Hebrew and Christianity. Then i got confused cuz i always thought they were the same thing. i really want to clarify this and also learn more about Islam's origins and how their traditions work.