How do you run an xcode project on ios simulator?

Sorry, this is a very basic question. The reason I ask it is that I am having difficulty understanding the instructions in the ios dev library. I try to follow its instructions and It doesnt work.

I am running xcode 7.2.1

https://developer.apple.com/library/ios/documentation/IDEs/Conceptual/iOS_Simulator_Guide/GettingStartedwithiOSSimulator/GettingStartedwithiOSSimulator.html

Running Your iOS App

When testing an app in Simulator, it is easiest to launch and run your app in Simulator directly from your Xcode project. To run your app in Simulator, choose an iOS simulator—for example, iPhone 6 Plus, iPad Air, or iPhone 6 + Apple Watch - 38mm—from the Xcode scheme pop-up menu and click Run. Xcode builds your project and then launches the most recent version of your app running in Simulator on your Mac screen, as shown in Figure 1-1.

I opened the simulator and choose the iphone 6+ then I went to scheme (Product > Scheme) but there is no way to choose my simulator from here I only see my project.

Thank you in advance for the help