Head over to DirectNIC and login.
Once logged in hit on Manage Domains
Select the domain you wish to forward to your 000webhostapp URL
On the right of the page you’ll see
Type in your 000webhostapp URL for forwarding to
You can use forwarding with or without masking.
Once setup your domain will automatically redirect to your 000webhostapp URL
Depending on if you picked masking or not it’ll retain the 000webhostapp URL in the address bar with SSL/HTTPS lock.