Hi burton,
If you right on the graph that contains your data, theres an option that says write file. I'm not sure if it has the s2p format but theres another way that should work.
There's a button on the graph window (file tool menu?) thats I think the rightmost on the line of buttons like file, edit and etc. You should be able to find a data file tool in the menu and that definitely sets you convert and write files in the format you need. And then you can import the file you want in another software.
Hope this helps.
Ananth.