When you relate your tables in the data connection, you create the relationship between the tables. Your tables, in your database, should have a key that relates them. For example, your parent table might have a column called ServerID. Your child table would have a column called ServerID as well, and each row in the child table would contain the server id of the parent table.
Try this -- after making sure you have appropriate table relationships in SQL for your tables, create a new form off the database. Connect your tables in data connection. Grab the folder from the data source that contains both tables, and drag it over to a blank view and create a new section with controls. Seeing how InfoPath sets things up when you let it decide may help you see how to set them up on the form you've already created.