There are lots of ways to see what your public IP address is, but the quickest is to ask Google, Bing or DuckDuckGo "what is my ip".
You can also go to ip.blockerdns.com and your public IP will be returned in plain text format. You can use this for automation scripts and other cases where you may want easy programmatic access, and it's worth noting that this has nothing to do with your blockerDNS account, or even whether you have an account. Google offers an identical tool at domains.google.com/checkip.