Here are Picun's own instructions, from the Picun website:
"How do I pair Picun wireless headphones?
To pair Picun wireless headphones, turn them on and hold the power button until the LED indicator flashes red and blue. On your phone or device, open Bluetooth settings and search for available devices. Select your model (e.g., F8 Pro, B12, P26) to connect. Once paired, the LED light will stop flashing and remain steady. Most models remember your device, so they’ll connect automatically the next time. If pairing fails, reset the headphones by holding the power button for 10–15 seconds and repeat the process."
To open Bluetooth settings on a Windows 11 PC ...
Go to Start > Settings > Bluetooth and devices > Bluetooth > On
... and search for available devices ...
Click on "Add device"