Are you asking how to add kanji to an existing kanji schedule? Say I found 足 in the dictionary and want to add it to my schedule. Before the list of words that use it, there is a box with a light bulb, plus sign, and a circle with a line through it. Click the plus to pull up a list of schedules it can be added to, then simply check one. If you don't have a kanji schedule to select, you can make one in "manage schedules".
In general the plus sign will add terms to schedules. It can be in slightly different places depending on what page you're on.
I think they may mean that they just want a study schedule for kanji. If that's the case, tap the "Manage your schedules" link that is below your current schedules, and you can find kanji schedules in there to add :)
If both of us are off, let me know and I'd be happy to help further.
