After connecting the two computers directly by crossover cable, the network adapters need to be given an IP address and there are basically two ways that this can be done:
1) Internet Connection Sharing.
If you are intending to share a broadband internet connection, you will enable "Internet Connection Sharing" on the actual Internet connection (modem connection) in the "host" PC. When you do this, Windows will allocate the fixed IP address of 192.168.0.1 to the Local Area Connection. The "client" PC's Local Area Connection should be set to get its IP address automatically, which it does by DHCP from the "host".
2) Manual Configuration.
If you are not setting up "Internet Connection Sharing", you need to allocate IP addresses manually to the two Local Area Connections using one of the ranges reserved for Local Area Networks, most commonly a 192.168.x.x subnet. Doing it this way, give the computers the addresses 192.168.0.1 and 192.168.0.2 with the *SAME* Subnet Mask address of 255.255.255.0
In each PC you need to set as "shared" in their Properties any folders that you want to have available over the network and, in any event, you should set at least one folder as "shared" in each PC.
Any firewall software needs to be configured to allow access to the networked computers.
That basically is it!