Seems cant connect to Blynk server

[PeteKnight]

@Neptune

Is there my problem of the code??

Yes, now your problem is being caused by your void loop and delays, instead of using BlynkTimer.
Read this…

Keep your void loop() clean

@Neptune

Also, if I would like to control light bulb(pin8) with the app, what should I set for it?? I saw people can set the pin when thay are using the old app.

Use a virtual pin, and read this…

Using Virtual Pins to control physical devices

I thought I’d write a guide about how to use virtual pins with app widgets such as buttons, to control physical devices such as relays, LEDs etc… Why use virtual pins anyway? I’d always recommend using virtual pins over physical pins when developing your code. There are a number of reasons, but here are what I consider to be the main ones: Virtual pins are hardware independent. This means that it’s far easier to port your code from one hardware platform to another in future (when you realise…

Pete.