interfacing serial to USB hardware

Do anyone have schematic how to connect (fisically) tx and rx arduino signal to a USB connector pins? thanks

what are you trying to do?

I explain what i want to do.

With arduino i ceck inputs and with if statement under true condition a led will on. After this i'd like to store event into files, memory, hd what do you prefer ;). I'd like to use rx and tx to send data by USB and i've seen on website someting related how to use these lines for usb but only for software point of view and i don't have any idea how to connect togheter

well, you cant connect them directly, usb uses differential signaling, and the processor doesn't support usb host natively, so you cant hook up any usb devices either without a crap load of programming that probably would end up using all your resources and end up being useless. people have had some luck using some external circuits to aid the process though. check this out.

http://www.circuitsathome.com/category/mcu/arduino/usb-shield

if all you want to do is make files on a usb drive, then maybe this might be more appropriate

http://www.mouser.com/ProductDetail/FTDI/VDIP1/?qs=sGAEpiMZZMubtgSkrSNnXGlLknVJb4BB5BuwPOOlWuA%3D

which has a code example here

http://www.arduino.cc/playground/Main/UsbMemory

Thank you of your very helpfull answers