Performance Monitor is an easy-to-use tool to record and monitor performance metrics. If you would like to measure IIS performance, you will need to add w3wp as an instance to your counter. What if there is no w3wp instance in the list?
The reason behind this is w3wp.exe is not running at that point. Once you browse a site hosted in IIS, this service should show up (after closing Add Counters window and opening it again).
A list of useful performance counters in .NET Framework is in this Microsoft documentation.
Your IIS server is struggling with performance? Check this post out: 9 Easy and Practical Recommendations to Improve IIS Performance