Have you tried to put your headset in pairing mode first? Anyway, in order to do it, starting with it turned off, press and hold the answer/end button for some 8 seconds, until the indicator light is flashing alternately in red and blue. It is in pairing mode now. Then, on your Android device, go to 'Settings > Wireless & networks > Bluetooth Settings', and, if your device's bluetooth radio is turned off, turn it on, by ticking the 'Turn on Bluetooth' checkbox. Then, on that same settings page, click 'Scan for devices'. After a little while, your headset should appear on-screen (most probably at the end of the list). By clicking over it, the pairing process should be automatically done. Otherwise, if a pairing mode (or PIN, or passkey) is requeseted, enter '0000' (four zeros). You'll see an inidication on that settings page that your headset is connected for phone calls.
By the way, if your headset's user guide happens to be missing, feel free to download it from
this location.
Please, let me know if you need further informations.
Regards,
Carlos