Thank you for the fast reply from my last thread
Cloudflare SSL is not working on my site
I also contacted their support group and they said,
We are seeing delays with our SSL certificate provider
So they reordered my certificate and is now active.
Right after, I followed @NGiNX reply of the steps
to change my Wordpress default website address
I got some infinite redirect issues on that, but fixed
by installing a plugin: CloudFlare Flexible SSL
But sadly, I have another problem.
Everytime I go to
entered the correct username & password, then
after clicking the Log In button > 400 error shows up.