Using indexes with 1.1

[Upayavira]

I've used code (see other thread - subject "To create indexes (warning: 
Xindice only)")  to create an index. But it doesn't appear to have made 
a difference to the speed of my app.

If I need to query a colleciton of 70 documents, all of the following 
format:
<doc>
 <title>Some title</title>
</doc>

with an xpath of /doc[contains(title, 'Some')]
How would I create an index that would speed that up? Do I just provide 
'title' as the field to be indexed? Or can I specify /doc/title? How 
does it know which nodes to index?

Thanks for any help.
Regards, Upayavira