Not sure exactly what you mean. But if you have a wired router and you want both computers to connect to the internet and share files with each other too... it is not difficult.
Internet box output to Router input. Desktop to router output number 1, laptop to router output number 2. Turn everything on and as for internet, it should already be working unless your router needs configuration. If your internet requires a password or your router needs to be setup, consult the manual it came with.
And as for file sharing between laptop and desktop, that depends more on the operating system than the router. If they both have the same Windows, just check the help menu on one of them computers about how to enable file sharing and you are done.
You can go to my network places and see any folders you shared. If you have Windows 7 on both PCs then sharing is even easier, just search the help for how to create a homegroup. If you have different operating systems, like one is XP and the other is Vista, the sharing will become a little more difficult. You will need to turn off password protected file sharing in the Vista menu for XP to read and write shared files easily.
If your router has WIFI and needs to be configured, consult the manual it came with on how to set up the network. Each router can be a little different.