1. What kind of communication you want to establish - ftp, www or something else ?
2. As the guy above mentioned you have to be sure that both PCs are in the same network let's say 192.168.1.0/24 in order to be able to see each other.
3. Most probably you have a firewall set up , which has to be taken into consideration also
So 1 step make sure that 2 ports which both PCs use on the switch are green
2 make sure and if needed assign IPs from the same subnet - for example PC A-> IP: 192.168.1.100 Mask: 255.255.255.0 (24 bits mask);
PC B IP: 192.168.1.101 Mask: 255.255.255.0 (24 bits mask);
3 from PC A type in command shell ping 192.168.1.101
if needed change settings of the firewall to allow pings
AS long As you make ping workable you have your connection at level 4 (Transport)
Further settings needed for upper levels applications required like FTP, WWW, which I'm sure you know how to do it