For LAN connection, do the following:
Click on start
On the search bar type cmd or navigate through folders and find your command prompt
On your command prompt type ipconfig /all (Take note of the IPv4 Address that would be your server's IP, write it down)
Now open ...\conf\char_athena.conf and ...\conf\map_athena.conf
See the codebox below, follow what was written. On your char_athena.conf find these lines:
// Character Server IP
// The IP address which clients will use to connect.
// Set this to what your server's public IP address is.
char_ip: 127.0.0.1 <<< Remove '//' and change 127.0.0.1 to your IPv4 Address/Server's IP
On your map_athena.conf find these lines:
// Map Server IP
// The IP address which clients will use to connect.
// Set this to what your server's public IP address is.
map_ip: 127.0.0.1 <<< Remove '//' and change 127.0.0.1 to your IPv4 Address/Server's IP
Don't forget to save the changes and compile source.
Finally you have to create your own clientinfo.xml and place it in your Data folder
Note: If you want others outside your network (LAN), instead of changing your IP to server's LAN/IPv4 address, use your public (WAN) address.