I hope you don’t have to figure out where each show is in the park, then pretend it is a break to schedule shows.
They show up as options when they are listed on Disney’s schedule.
You have to go back into your plan and “add attraction” unless I missed something they don’t show up when you initially pick attractions!
If you’re talking about things like the live shows in WS, they can be added to a TP. For ones that show at multiple times, select the time that you want. That being said, I rarely make a TP for an afternoon/evening I plan on spending in WS; I have a separate list of the show times and plan on being at the right place at the right time.
Adding to the others’ advice, when you make your TP, the rides and main attractions show up on the first page. There are other tabs at the top of the page for other attractions, such as the Holidays Around the World shows once they’re scheduled.
For all shows etc which have a schedule, once you include them, you can choose the time of the one you want to see.
On the first page when you pick to personalize a plan, there are tabs across the top that read headliner attractions/entertainment, shows/parades/diversions, and seasonal items. You can use those tabs with the +/- options instead of having to add them one by one when you get to your step by step plan.