To access QPI, you simply need to click on the database you want to work with. Once you click on your database, scroll down in the portal to Query Performance Insight(QPI). Once QPI opens, you will see three options to sort on: CPU, DATA I/O, and LOG I/O. You can also set the timeframe to view, I set for 24 hours. Now, I have my timeline of 24 hours, and I am able to view which queries had the highest DATA I/O. I made a list of the top 3 from each category(CPU, DATA I/O, and LOG I/O) and presented it to my client. I presented the number of times it was executed, and the usage it utilized each time(all from the QPI information). The client then sent me 10 queries they wanted tuned and listed them in a prioritized list.
Well, by the end of tuning their 3 highest priority queries, we removed over 10 billion logical reads! Yep, 10 BILLION! The client was very happy with our results and is currently awaiting the preview Standard Elastic Pools to come out of Preview and become GA. I have provided a few screenshots of an AdventureWorksLT database on my personal instance just to show you how to access QPI, and change metrics.
Click through for a demo.