Joomla is a content management system/framework. If you just want to host static HTML you can just spin up a droplet using the default Ubuntu image, ssh into it and run:

apt-get update
apt-get install apache2

This will install the apache web server. You can then drop your content into /var/www/html using an SFTP client like Filezilla. Once your content is in that folder it will be accessible via a web browser.

(Alternately you can use the LAMP image when creating your droplet which already has apache installed but also includes PHP and the MySQL database server)