SharePoint Developer Dashboards are easy to use and follow. Think of these dashboards as Fiddler Lite. For more information you can go here for SharePoint 2010 and here for SharePoint 2013.
The overall steps to start the Developer Dashboard are
1) If you have not already, configure and enable your Usage and Health Data Collection Service. For more info click here
2) Once you have your app up and running, execute the following PowerShell Script
$svc = [Microsoft.SharePoint.Administration.SPWebService]::ContentService
$dds = $svc.DeveloperDashboardSettings
$dds.DisplayLevel = "On"
3) If everything worked you will see
4) From there you can find out page information, SQL query calls, etc.
An extremely useful tool especially if you are troubleshooting performance.