Hi, Tony, and welcome,
On the assumption that this is compiled HTML Help (.chm), I'm
afraid that the help viewer isn't customisable to that extent. You
can have one Index tab only, labelled "Index" or its localised
equivalent. Anything else would require you to create your own help
viewer, which obviously requires programming skills.
One thing that may be worth noting is that each window type
in an HTML Help project can have a different index file associated
with it. So, if you were to set up three different window types,
you could associate a different index with each one. I'm not sure
that this gets you much further, though.
Pete