If both computers are connected to a router, then they are already "networked".
Set any folders that you want to have available over the network as "shared" by right clicking and selecting the Sharing & Security option. In any case, at least one folder should be set as shared in each computer to help to get them communicating. Any firewall software needs to be configured to allow access to the networked computers, which may involve adding their IP addresses in a trusted area.
As regards the DVD writer, set that as shared too, although I don't actually know if it is possible to burn CDs/DVDs with a remote PC over a network.
NETWORK PRINTER SETUP:
1) Connect the printer to the "client" PC, as though it were to be used with that computer, and install it. This ensures that it has all the necessary software/drivers on board.
2) Reconnect it to the "host" PC and, in its Properties, set it as "shared". In the client's "My Network Places" (or Network Neighborhood), the printer should then appear as a shared resource of the "host" PC along with any shared folders. Double clicking the printer in the remote PC should automatically install it as a "network printer" in the "client". This means that the "client" now has the same printer installed twice - once as a "local" printer and again as a "network" printer (with a bar under the icon to indicate a network device). If you are always going to print via the network, you may want to set the "network printer" as the default.
Otherwise, have a look at this Microsoft article. It is an old article written for Windows 95, but the basic principle for installing the network printer should still be valid - click here