Adding individual characters to make a custom list

My son gets a list of 10 characters a week. How can I search for individual characters and create a custom spelling/writing list?

I’m using the Android version of Skritter but I cannot work out a way except by going through the lists and waiting for a character I want to appear by luck so I can star it.

EDIT: OK! I’ve worked it out! But the “add section” button is very small and it appears in the corner which is why I didn’t notice it!