Did you install Word Press?
Have you logged into the WP admin and try to change themes?
The new theme files need to go into a folder in your wp-content/themes folder
( wp-content/themes/NewThemeFolder )
You say you uploaded to your cpanel?
Not sure what you mean, cpanel is your site manager.
The zip file needs to go into your wp-content/themes folder
then click on it and extract and it should create a new theme folder
If you put the zip file elsewhere it would be better to remove it and upload it to the wp-content/themes folder.
If you use cpanels file manager, click on the zip file, and on the right select extract.
A new window will open showing the extracted files. Close it, you should now see the new folder.
I use an ftp program like CoreFtp as its easier than File Manager.
I uncompress the zip file on my computer and then with ftp program I select the wp-content/themes folder on my site and drag the new theme folder from my computer over to the wp-content/themes folder.