We instantiate the ttk.Notebook with a fixed size, and then loop over a dictionary with some predefined data that will serve to create the tabs and add some labels to each region:

import tkinter as tk
import tkinter.ttk as ttk

class App(tk.Tk):
    def __init__(self):
        super().__init__()
        self.title("Ttk Notebook")

        todos = {
            "Home": ["Do the laundry", "Go grocery shopping"],
            "Work": ["Install Python", "Learn Tkinter", "Reply emails"],
            "Vacations": ["Relax!"]
        }

        self.notebook = ttk.Notebook(self, width=250, height=100)
        self.label = ttk.Label(self)
        for key, value in todos.items():
            frame = ttk.Frame(self.notebook)
            self.notebook.add(frame, text=key, underline=0,
                              sticky=tk.NE + tk.SW)
            for text in value:
                ttk.Label(frame, text=text).pack(anchor=tk.W)

        self.notebook.pack()
        self.label.pack(anchor=tk.W)
        self.notebook.enable_traversal()
        self.notebook.bind("<<NotebookTabChanged>>", self.select_tab)

    def select_tab(self, event):
        tab_id = self.notebook.select()
        tab_name = self.notebook.tab(tab_id, "text")
        text = "Your current selection is: {}".format(tab_name)
        self.label.config(text=text)

if __name__ == "__main__":
    app = App()
    app.mainloop()

Every time you click on a tab, the label at the bottom of the window updates its contents, showing the name of the current tab.