Under normal circumstances, when the Bluetooth headset enters the pairing state, you only need to press and hold the power button for about 10 seconds, and the headset will turn off to turn on and then turn on to the pairing state, which is manifested as the headphone indicator red and blue alternately flashing (some are long lights of one color). Then use your phone to search for Bluetooth devices to find your headphones.
After the headset enters the pairing, the mobile phone should search for the Bluetooth device, the general mobile phone can search for the headset in about 5 seconds, and then select the Bluetooth headset device you find on the mobile phone, the mobile phone will prompt you to enter the password. Most mobile phone passcodes are 0000 or 1234, but there are some that are specially set by the manufacturer, which will be detailed in your headset manual.