mini usb to 3.5 mm female jack converter

please tell me how to make a converter(without any purchases) so that i can connect my 3.5 mm jack headphones to my phones mini usb port which is 2 in one charger and audio out port

My phone-htc touch 

i thought out of something like this

thank you in advance

Here is the pin out of that connector. That should give you all the info you need. The tip of the jack is typically the left channel, the center ring is the right and the base ring is the ground. You should be able to figure it out from there.