@Ryan R if you create a netlist on an incomplete schematic with no ports, all nets that are undriven or nets that have no destination (driven but going nowhere) will be colored (highlighted). Pressing ctrl-j will immediately let you add the missing ports. Of course you need to inspect if the added ports are the ones you want. In some cases you have a driven net but you don't want a port for it. These adjustments can be done manually by adding / removing ports.