Download the wp-magazine.zip file from https://wordpress.org/themes/wp-magazine.
- Log-in to your WordPress site and open the Dashboard.
- Go to the Themes tab and click on Add new.
- Now choose the .zip file you downloaded early.
- Click on Install Now and Activate

Make sure that you also install and activate the recommended plugin. You will get a demo import plugin which will help you import the demo website in just one click.