There are many ways to Download Xcode to your mac book, the easiest way is, to download Xcode is via Mac Appstore. Even though it is the easiest way, it is slow, most of the time. Download Xcode DMG File Via Apple official site Visit https://developer.apple.com/download/more/ link to Download such as Developer Tools
I thought to give you some ideas about new mobile development projects. If you are new to mobile development, you may be thinking to establish a new and unique mobile app. Its good but my concern is 99% of your ideas are already implemented and hosted in Appstore or Playstore or Amazon Store.