Hey there! Is your site set up on another control panel? If so, our Transfer Tool automates the process of moving from Plesk, Ensim, or DirectAdmin:
This interface copies multiple accounts from a remote server to your cPanel & WHM server.
docs.cpanel.net
If you aren't currently using a control panel and the site is just written in HTML, you can likely just upload the files to a server using cPanel and I would expect that to work. If you have more advanced features you need to move (email, databases, etc.) you can use the following guide to make sure those get set up in the proper are on the cPanel side of things here:
This document describes how to migrate your web accounts from unsupported third-party control panels to cPanel & WHM.
docs.cpanel.net
Let me know if that helps!