Hi, Look for Softaculous Auto-Installer in your Cpanel, and then search for OpenCart. Then install and thats all.
Yes, almost every hosting provider offers free Softaculous auto-installer. In case your does not, just visit www.opencart.com, download the e-commerce platform. After that, all you need to do is inzipping the downloaded folder and copy all files to your server using FileZilla or any other FTP program. The last step is to visit your domain and start the installation. Before that, you must have created a database and enter its requisits during installation. If you need any further help, we bet that you know what to do!
Sometimes Cpanel may not have the latest version so installing manually as described above will always make sure you have the latest version. Only takes about a minute. Also, I usually upload the installation zip file through file manager in cpanel and then uncompress on the server. Not sure if that could cause any problems but it takes me much longer to upload the uncompressed install files through filezilla. You just have to make sure you move the files to the public_html folder from the defualt "upload" folder where they are compressed.