The websites they provided aren't creating an IP for you, they're just telling you the IP address your internet provider has already assigned you.
ceagle2 provided some good info on setting up a custom IP / domain thing, but most private minecraft servers probably don't want to be doing that.
All you need to do is get your computer's IP (which is what google and sites like whatsmyip will tell you if you go to them) and the port you setup in port forwarding. Putting the two of them together should give you something that looks like
Assuming that everything is set up correctly, your friends should be able to put that into the server connection box and connect. (Friends connecting from the internet will need your public IP, as in the one revealed by asking google what your IP is or going to sites like whatsmyip. Friends on your LAN can connect using your internal IP)
(FYI: Checking your ports from within windows will give you your IP address within your home network. It usually won't tell you what your IP is in regards to the internet. If you are getting an IP that is along the lines of 192.168.0.202 or 192.168.1.100, then that's your internal network IP. Someone trying to connect to your server from on the same network will use that IP address to connect. (for instance, your friend sitting at the desk next to you at home plugged into the same router)
Side note, if everything seems to be working fine, people are trying to connect, but get authentication errors, try checking your firewall/virus scanner settings. Some virus scanners will set unknown programs, like the minecraft server, to be "high restricted" programs, which means they'll let them run, but will deny them access to the internet. Check your settings to allow the server through the firewall, and/or manually reclassify your the minecraft.server.1.8.exe (or .jar, as appropriate) to either low-restricted or "trusted". Either one should let it make the connections it needs.