Login into your CPanel
Often you can access your CPanel just by adding /cpanel to your domain name ... example.com/cpanel
Access the File Manager
Although your screen may not look 100% identical to the one above, every version of Cpanel does come with a "File Manger" option somewhere.
Choose to Go to the Webroot
Find htaccess.txt
Your files and folders will be listed alphabetically. Scroll down until you find htaccess.txt
Check the box next to htaccess.txt and click "Rename" at the top of the page.
Change the file name to .htaccess
Enter .htaccess as the new file name and click "Rename File"