I would recommend Grav for a simple website, it is very lightweight - I’d recommend checking out their demo before installation.
If you want to install then do the following
Make a new site if you don’t have one already
Head over to Grav and download the .zip install https://getgrav.org/download/core/grav-admin/latest
Read the installation if you need to - https://learn.getgrav.org/basics/installation
Head to your File Manager and start uploading
Upload your .zip file from earlier
If you want you can use FileZilla or another FTP client instead…
Once uploaded use a PHP script like this to unzip it https://github.com/ndeet/unzipper/blob/master/unzipper.php
Or you can use the built in function of the File Manager to extract the files into public_html
Now once extracted ensure all the files are visible in the public_html folder!
Visit your website to perform the simple installation!
Tada! The system is now installed!
Visit your site and you’ll see it is running fine!
Hit PAGES > EDIT in the Admin Panel to begin the creation of your site!
There are various themes and plugins available via their website and other content creators too!
I hope this is some help - there are tons of content management systems out there to choose from - the task is finding one that works for you!