1. The first thing we need to do is open up Qt Creator and create a new project. If this is

　　the first time you have used Qt Creator， you can either click the big button that says

　　New Project with a + sign， or simply go to File | New File or New Project.

　　2. Then， select Application under the Project window and select Qt Widgets Application.

　　3. After that， click the Choose button at the bottom. A window will then pop out and

　　ask you to insert the project name and its location.

　　4. Once you‘re done with that， click Next several times and click the Finish button

　　to create the project. We will just stick to all the default settings for now. Once the

　　project has been created， the first thing you will see is the panel with tons of big icons

　　on the left side of the window that is called the Mode Selector panel; we will discuss

　　this more later in the How it works.。. section.

　　5. Then， you will also see all your source files listed on the Side Bar panel which is

　　located right next to the Mode Selector panel. This is where you can select which file

　　you want to edit， which， in this case， is mainwindow.ui because we are about to

　　start designing the program’s UI！

　　6. Double-click mainwindow.ui and you will see an entirely different interface

　　appearing out of nowhere. Qt Creator actually helped you to switch from the script

　　editor to the UI editor （Qt Designer） because it detected the .ui extension on the file

　　you‘re trying to open.

　　7. You will also notice that the highlighted button on the Mode Selector panel has

　　changed from the Edit button to the Design button. You can switch back to the script

　　editor or change to any other tools by clicking one of the buttons located in the upper

　　half of the Mode Selector panel.

　　8. Let’s go back to the Qt Designer and look at the mainwindow.ui file. This is basically

　　the main window of our program （as the filename implies） and it‘s empty by default，

　　without any widget on it. You can try to compile and run the program by pressing the

　　Run button （green arrow button） at the bottom of the Mode Selector panel， and you

　　will see an empty window popping up once the compilation is complet