After clicking on Select you will be taken to the registration page. See the image below:
Fill the form by entering your preferred username, email and password. If you have a coupon code then select the checkbox and enter it too. Then click CREATE ACCOUNT. Clicking this button will take you to the Custom Domain step. See the image below:
Here you can select the primary level domain. You can select it now for which you have to select the domain you like which is free in this package, otherwise, click on Skip this Step →
Upon selecting your preferred option, click SELECT DOMAIN AND CONTINUE or Skip this Step →.
On the next step, you will be prompt to log in. Enter your username and password you had set up previously.
Enter your username and password and click Log In.