C:\User\user>mkdir ggyy
C:\User\user>cd ggyy
C:\User\user\ggyy>mkdir templates
C:\User\user\ggyy>mkdir static
C:\User\user\ggyy>copy  con  w9.py                    
from flask import Flask
from flask import render_template
app = Flask(__name__)

@app.route("/")
def webRoot( ):
   return '<font color=Red size=7>Hello World!      這是網站喔 !'

if __name__ == "__main__":
   app.run( '0.0.0.0' , port=33888)   # <== 注意這改用 33888 喔!
^Z           # <== 注意這是敲 CTRL_Z  表示 w9.py 到此結束
C:\User\user\ggyy>python  w9.py                    

C:\User\user\ggyy>pip install flask 
 . . .  (出現安裝 Flask 的信息)
 . . .
 . . .
C:\User\user\ggyy>python  w9.py