internet sharing problem

I can not share an internet between two laptops running windows 7 with any ethernet router at the moment. And I try to connect to internet by a 3G modem which connected via USB.

There is no chance when I have tried giving them specific IP adresses. I I saw two network connection which says "Home Network" and ethernet connections seems as "Unidentified network". Whenever I assing IP's manually, I can manage to get Home network but no internet connection, even I shared it on the network settings or even internet settings.

I think it's your set up or your ISP is? Are you want to share a 3G like cell phone?