added tkinter habit tracker skeleton

Author: Chloe White

mood_tracker/simple_calendar.py

@@ -0,0 +1,28 @@
+import tkinter as tk
+from tkinter import messagebox
+
+def main():
+    root = tk.Tk()
+    root.title("Habit Tracker")
+    root.geometry("400x300")
+
+    tk.Label(root, text="Habit Tracker App").pack(pady=10)
+    
+    tk.Label(root, text="Enter Habit:").pack(pady=5)
+    habit_entry = tk.Entry(root)
+    habit_entry.pack(pady=5)
+
+    def add_habit():
+        habit = habit_entry.get()
+        if habit == "":
+            messagebox.showerror("Error", "Please enter a habit")
+        else:
+            print(f"Added habit: {habit} (placeholder)")
+
+    tk.Button(root, text="Add Habit", command=add_habit).pack(pady=5)
+    tk.Button(root, text="Exit", command=root.destroy).pack(pady=5)
+
+    root.mainloop()
+
+if __name__ == "__main__":
+    main()