SubSurf toggle missing from mesh panel

I am new to Blender and am doing the quickstart chapter from ‘The Official Blender 2.3
Guide’ (building Gus). The SubSurf button is missing from the mesh panel, so I cannot
proceed. I am using Is this a difference in the

Thank you for any advice, suggestions.

yeah i ran into this too. Subsurf is in the modifier panel now

Remember version 2.3 is a few years old now and lots of changes have been made to the interface. Wherever possible look for more recent tutorial sites.