Just use your external ip address (not the internal 192.168.X.X IP) without specifying port 80 as that is redundant because port 80 is the default http port number.
Since it is not a static ip address, you could use dynamic DNS services such as noip.com. Or you could just check and update your ip address manually everytime you get a new ip.
As for embedding it on your website. A quick solution is to use the MJPEG stream coming from the ip camera and enclosing that in an image tag like this:
<img src="http://IP_ADDRESS/video/mjpg.cgi">
The downside to this is that IE does not support MJPEG streaming. Chrome and Firefox supports it natively. A workaround for IE is to install the Google Chrome Frame plugin for IE.