One place I can see the time table coming up biut unfortunately dont find a tab which says purchase or proceed.
Are you looking via
Czech Raiways eShop? Or maybe just Czech Railways timetable page?
Would be helpful if you can send me the direct link for this, am not sure if its possible though.
Direct link isn't possible when it gets to any particular connections, it just won't show up and you'll have to input all the data once again from the beginning, thus the above link for a eShop is the starting point
Anyway, what date are you looking at? Maybe it's not possible at all at the moment, because all the discounted tickets got sold out