Your project should have been created, you just have to compile it in Visual Studios before you can open it. Press the open Visual Studio button or Open your project solution which should be in your Unreal Projects folder. Change it from debug to Development Editor and right click your game project in the solution editor and go to properties and in the vc++ dependencies tab. set all empty to inherit from project defaults. then build your project.
Once it is compiled you should be able to open the editor with out a hitch.