added main.py

main.py

@@ -0,0 +1,26 @@
+from PyQt6.QtCore import QSize
+from PyQt6.QtWidgets import QApplication, QMainWindow, QPushButton
+
+import sys
+
+class MainWindow(QMainWindow):
+    def __init__(self):
+        super().__init__()
+
+        self.setWindowTitle("Hello World")
+        button = QPushButton("Click Me!")
+
+        self.setMinimumSize(QSize(200, 100))
+        self.setMaximumSize(QSize(900, 800))
+
+        self.setCentralWidget(button)
+
+app = QApplication(sys.argv)
+
+window = MainWindow()
+window.show() # windows are hidden by default
+
+# start event loop
+app.exec()
+
+