I am not with Laminar Research; just a flight simmer.
The heading of your question suggests to me that you have downloaded the demo version. The demo version is the same as the full unlocked version but limits you to a particular airport and associated scenery and has a time limit once you elect to run X-Plane. When you place an order and then pay for X-Plane you will be provided with a password key. When applied correctly the demo version will unlock and provide a full comprehensive version of X-Plane.
The official version of X-Plane from Laminar Research is complete with aircraft, scenery and air ports. To get up and running you don't have to make additional purchases. It is a complete package as far as software is concerned to be able to run X-Plane. The only items that you will have to purchase will be hardware and that will depend on what you want to use and what funds you have.
As you become more proficient in running X-Plane and want to become more adventurous then proceed with additional features.
In your reference to an instruction book I assume you are making a reference to the X-Plane Users' Manual This can be found as an on-line document at the following link at https://www.x-plane.com/support/manuals/ and a version in English can be viewed at https://x-plane.com/manuals/desktop/
Welcome to X-Plane.