go into command prompt and type ipconfig. This will give you your IPv4 address, Subnet mask, and default gateway.
Depending on your ISP provider your IPv4 and default gateway can change. At home i use comcast and its default ip and gateway are 10.0.0.x while at work we use 192.168.1.x so you will need to know exactly what your using.
1)For windows 7 down in the bottom right by the clock will be a network icon.
2)Right click on it and click on open network and sharing center
3)in the middle of the page will say view your active networks, click on Local Area Connections on the right and a new window will open up.
4)click on properties, a second window will open up, Click on Internet Protocol Version 4 ( will highlight blue) and click properties just below the window.
5) in the 3rd new window click on the Use the following IP address and then fill in the boxes from what was given to you in command prompt.
for example..... these are my settings at work, yours will be different
IP address 192.168.1.10
Subnet mask 255.255.255.0
Default Gateway 192.168.1.1
Then for preferred DNS server use 8.8.8.8
Windows 10 you can follow the same steps
Say you use 192.168.1.10 for windows 7, then use 192.168.1.11 for window 10
If you ever run into issues you can always just click the Obtain an IP address automatically and your modem will then assign you a ip address.