Open your terminal and run the following command.
npm install strapi@alpha -g
If you encounter npm permissions issues, change the permissions to npm default directory.
Use the built-in CLI to generate your first project. Run this command and wait until the project is created.
strapi new myProject
Then, enter in your project.
Now, you have to use another command of the CLI to run the server. And you will be done!
Open your browser and go to the administration panel (http://localhost:1337/admin) to create the first user.