So, I did set up my blog and followed the steps tu setup the DNS on the domain. All is working, but I saw that the web is marked by unsafe by the browser. It says that the domain certification is not trusted.
I was using another domain, and now I just changed it to a new one.
I contacted the domain provider, and they told me it is because the domain is pointing to the IP indicated by write.as in the steps of setup, and that is a problem of the provider of write.as, since the SSL certification is installed there.
Any idea of how can I solve this?