The drop-down box for a lossy transmission line has the lines:
What do I enter on these lines? I looked in Help, but couldn't find any information on this.
There is a vast Getting Started guide which provides all the necessary information related to the items in the application. I've looked through the manual and found that Lossy transmission line is also explained. I recommend downloading the manual using the link posted below. It's a PDF file which means you will also need a PDF compatible reader installed.
-Download user guide: http://cds.linear.com/docs/en/software-and-simulation/LTspiceGettingStartedGuide.pdf