if you buy the CPANEL license, it comes with the instructions, the script to install it and even the video tutorials to use it.
If you purchased the dedicated server with cpanel installed, tell those of the company where you purchased it to help you configure since they are giving you the dedicated with cpanel, it is their responsibility, give you and offer you all the help.
here is the Introduction to cPanel setup and how to install cPanel correctly.
https://www.youtube.com/watch?v=6uR4JLjEDRs