Setting up Raspberry Pi Pico with Arduino IDE
1. Download and install latest Arduino IDE.
2. Run Arduino IDE, from Tools => Boards manager, Type pico and Install "Arduino Mbed OS RP2040 Boards" package.
3. On the IDE, from Tools => Board => Arduino Mbed OS RP2040 Boards, select Raspberry Pi Pico board.
4. Now while holding the Boot Sel button on the Pico board, connect the board to USB.
It will automatically Detect your Pico Board.
(This needs to be done when you connect the board first time. Next time, just connect it)
Now, From Tools => Port, Select COMxx (Raspberry Pi Pico), In our case COM5.
5. Open example file Blink. File => Examples => Basic => Blink
Compile and Upload,
The Onboard LED should Blink now.
Note: If the Computer does not recognize the Pico board, try to connect to different USB port of the PC.