scooby is correct on those points, pretty straightforward setup. To set your IP addresses you can use ipconfig (from a command prompt) or via the GUI using the following steps:
Apologies for any omissions, this is from memory and is for XP, but the options are the same in 7/Vista, just called Network and Sharing center instead
1) Open Network Connections
2) Right-click ethernet adapter and select properties
3) IPv4 option in the center window (choose from Windows Client, IPv4, IPv6 and a couple of others)
4) select the 'assign IP address manually' radio button and use whatever address schema you wish, conventionally 192.168.1.2 up to 192.168.1.254 with 255.255.255.0 as your netmask, 192.168.1.255 as your broadcast and 192.168.1.1 as your gateway (this is the address of your router typically, but the gateway doesn't matter for your 2 machine setup - THE OTHER TWO OPTIONS (netmask and broadcast) DO!)
On a tangential note, what about telnet are you trying to 'practice' - there is practically nothing involved (which is what makes it so insecure and obsolete these days), probably worth trying SSH afterwards for something that you'd actually use on a daily basis.