In general, a 192.168.x.x IP address is going to be an internal network address. Your router assigns those to the devices connected to it.
Your ISP IP address will be assigned by your service provider to whatever device connects you to the Internet, and is the IP address that can be "found" by someone connecting from somewhere else on the Internet. The easiest way to find it is to go to a site like whatismyip.com while you're on the network. (Alternatively, you're looking in the settings for the device that actually connects to the Internet and looking for a WAN IP. If the WAN IP is a 192.168.x.x, then there's another device between it and the Internet.)
In order to access the cameras directly from across the Internet, they'll need to have unique port numbers, and those ports will need to be forwarded from each "routing" device on your network along to the camera.
For instance, if your modem is also your router, then the ports just need to be forwarded there.
If you have a modem and then a router, you'll need for forward the ports first from the modem to the router, THEN forward them from the router to the camera itself.
There's two ways to do this, depending on what your specific needs are.
In my case, I left all my cameras with port 80, but had my router forward requests for port 801 to one camera's 80, port 802 to another camera's port 80, and so on. Before that, my modem forwarded requests on port 801-803 to the router.
The problem with this is that the cameras don't know they've had port 801 (or whatever) opened instead of 80, so they can't report it themselves automatically, though that doesn't really seem to matter for my usage.
The alternative is to change the port settings for each camera to a unique port, and have the modem and router forward those ports along as appropriate. The problem here is that now when you want to access the camera on its own network, you have to add the port number on, when you wouldn't normally have to. (192.168.x.x:801 instead of just 192.168.x.x)
There. Clear as mud?