Assigning a datasource for a TREX index

I'm trying to create an index to search an internal web site at my company. I've created a web crawler, a web repository and other necessary items. Following the instructions I have to create the index, I need to set the data source of the index to the web repository I created earlier. However, when I try to do this I'm presented with a list of directories. Presumably my repository is listed somewhere in this directory tree. But I have no idea. Am I doing something wrong? Which directory should I look in to find my repository?