Windows XP, How do I Batch enter Picture, Authors Name

I have several thousand pictures I have taken
over the years and Using Windows Xp
Explorer when I click on a picture name
or thumbnail, one of the options is "properties",
in the properties page there is a summary tab,
clicking on the Summary Tab one picture at a
time allows me to enter my name as author.
When I select 2 or more pictures at a time I can
access the Summary page but the data entry
boxes are shadowed and will not let me enter
my name. Is there a way to enter my name in
a batch of picture files?

Thanks!