To get yourself a free subdomain, register an account at https://frii.site/account.
Afer that, go to the dashboard, and register a new domain by typing your domain (ex: super-awesome-domain.frii.site) to the "Register a new domain" field, then click the magnification glass icon. Make sure to refresh the page after this to show the changes
Managing your domain using frii.site is very easy.
Select your domain on the dashboard, and click the type dropdown. 
Make sure to set a value that is appropriate for each type. Hit the "save" button after this.
Changing your domains "content" is by changing the value field. 
Sometimes you don't want to own a domain anymore, in that case hit the red recycle bin button next to the save button. You have to wait 15 seconds to confirm this action. 
Deleting your account can be done in the account settings.
Hit the "delete your account" button there. 
This will give you a 15 second countdown
After the countdown is finished, you will get an email confirmation about deleting your account. If you wish to delete your account, open the link.
You can download the data we collect about you by pressing the "Download data button" in the account settings
After a short while, you should see that a download has started for your account data.
More info can be found on our wiki