How to assign an existing line to a Grasshopper element/code, urgent

I have a Grasshopper code and now want to assign a line from an existing Rhino7 model to an element to apply the Grasshopper encoding to the existing model.

Can someone tell me the best way to do it? I’m new to Grasshopper and haven’t figured it out yet.

Please help me, it’s urgent! :slight_smile: