Creating a polyline from generated data.

Hi there, I'm new to grasshopper and following a tutorial on how to generate a parametric truss. I encontered a problem creating polylines from generated data. I want to input 4 grasshopper points (generated) and feed this to a PLine but the PLine item is accepting only one value and when connecting the second generated point the previous path is replaced with the new connection. The tutorial shows the 4 items feeding stright to the PLine item I can connect only one. Is there a setting I need to tweak in the PLine to accept more than one item? Thanks for your help.
Rob