Issues with capping this surface please help

Hi There,

Can you please help me cap this extruded curve, I’ve read the available rhino blogs on capping and youtube videos and I can’t figure it out. Your help will be much appreciated. Thank you!

Screenshots do not help us much, please post the Rhino file… I suspect that your original curve might not be planar, thus Rhino cannot cap your extrusion with a planar surface.