Talk to the people at your site to learn what types of documents contain the information they need.
For example, assume you are developing a topic design for people in the medical industry to find information relating to current drug testing. Based on discussions with the people who will use Verity search agents at your site, you learn that the following types of documents are prime sources of current drug testing information:
Research reports
Product literature
These documents form the information sources to be searched by Verity search agents.