Launch the Add Test Nodes Wizard by selecting  Wizards > Add Test Nodes  from the main menu.

In some cases such as testing over remote networks you will need to manually add a node by IP address.  This can be easily accomplished with the Add Test Node wizards.

Enter the IP address of the remote machine.  LanMarkXT must be running on that machine and the machine must be accessible from the test machine.  Click Add Node and check the status window at the bottom of the wizard to see the status of that node.  Once the node has been added click finish.