On the 'Seminars' page, Click the 'Book Now' block on the right side of the price of the event. 

You will then be guided to a page with a calendar. On the calendar, finad the day of the seminar (August 26) and click it. (The day should have a dot pinpointing it.)

Once you click the day, a time slot option will pop up on the right side of the calendar. It should say '11am'. Click that time slot button.

Once you click the time, select the 'next' button on the right-hand side and then proceed to checkout.