From your question it is not clear to me what exactly you are looking for. Could you please elaborate? Are you looking for some demo csv files that should come with Informatica installation? AFAIK there are no such files.
If this question is still unanswered, I hope the following will help you.
If the source is already imported into a mapping, you can look for the source file directory under session configurations:
- Open Workflow Manager
- Double-click the session
- Under Mapping, click on Sources
- "Source file directory" will point to the path.
By default, the source file directory would be $PMSourceFileDir\.
On the AdminConsole, for the Integration service associated to the workflow, under Processes, the value for $PMSourceFileDir\ and $PMRootDir can be found and if required, updated.