The socket on your bluetooth headset is for charging purposes only, through either one of your PC's USB ports (your PC won't recognize it as an e.g. pendrive), or the mains charger. It is not meant to be charged via your phone's port, whatsoever.
Anyway, your headset is able to pair with up to 3 devices (phones, computers, etc.). If it has already been paired to 3 devices, its memory is full. In this case, reset it, by pressing, at the same time, these 3 buttons: volume (+),. the volume (-) and the MFB, whilst in idle mode (i.e. not connected to another device). Then, it will automatically enter the pairing mode, denoted by its indicator light with a fast flashing. Otherwise, i.e. if its memory is still idle, starting with it turned off, press and hold the MFB for some 6 seconds, until the indicator light is steadily lit, and then, with a fast flashing. Either way, make your phone's bluetooth application search for new devices. After a little while, your headset should appear on-screen. Select it and make it connect. If a pairing code (or PIN, or passkey) is requested, enter '0000' (four zeros). If the pairing process is successful, your headset should enter the stand-by mode. There could be an indication on your phone too that a headset is connected. The pairing process between any two bluetooth enabled devices should be performed just once. All subsequent connections between them should be achieved by bringing them both within each other's range, with their bluetooth radios turned on, of course. Otherwise, at most, a simple press on your headset's MFB should suffice.
Hope it works for you.
By the way, if your headset's user guide happens to be missing, feel free to download it from this location
Anyway, please, let me know if you need further informations.