This is easy to do for most home routers.
Here are three methods listed from hardest to easiest as the hardest should always work:
Long way that should always work:
1. Open a Commmand Prompt.
2. Run the command ipconfig /all
3. Read the gateway ip address and write it down.
4. Open your web browser and go to http://gatewayip/
For most new home routers that will be http://192.168.1.1/
5. There should be a model number listed in a password prompt. Write it down.
6. Cancel the password prompt if it's a popup.
7. Read the model number and search Google for the model number.
8. You should be able to find information about the manufactour and the features that router model has.
A. For a newer D-Link home router with the default configuration you can skip to step 4 above and use http://192.168.1.1 and skip step 6 above.
B. For any router with UPnP enabled, you can just go to Network Places in Windows and the router will appear and you can skip to step 7 above.
A/B. Covered by ScottW and raphoenix above.