Jeff,
I will make this as short as I can.
Check with your ISP to see if port 80 is blocked. If you are using business grade service, it should not be. But you can use something like port detective to find out if you don’t want to call your ISP.
If port 80 is not blocked, you need to log into your lan router and do a port forward of port 80 to your windows server. I can’t tell you exact because I don’t know which router you are using. But find this in your LAN router.
Once you have setup port forwarding from your outside to your inside server on port 80. Go to any computer and put in your outside address http://70.196.23.145/openemr.
This is the quick and dirty way to get outside access to your OpenEMR. But I will warn you that this is the most unsafe way to do it. There is a lot more to opening your emr to the world. You can use a self signed certificate go to administration->Other->certificates to secure your site with SSL.
I can write more but then this will not be a short answer.