Click the Ancient Wonder icon on your bottom bar and it will bring up a menu with all the Ancient Wonder listed. You will have to scroll through the pages un till you get to the one you want, click it and it will go to its menu were you can add runes to its wheel and build it
Edit: the icon you are looking for is a circle with 6 shields surrounding it and when you hover over it, it says Rune Shard Overview, at least that is where its located at and what it looks like on the PC version