Connection of serial pin on ATMEGA328P to connector B type(female) D+ and D- Now I am using ATMEGA328P and want to communicate with computer in serial using B connector female (also want to provide power from computer to ATMEGA328P using B connector). 

So here is my question. How can I connect D+ and D- to ATMEGA328P's pin No. 2 (PD0/RX) and pin No. 3 (PD1/TX)? In other words which pin should I connect to D+ and D- ? Also is it possible to connect them directly?

Thank you in advance.
The Arduino Uno (and similar boards) have a chip on them that does serial communication via a dedicated USB chip (the ATmega16U2 chip). You can't just connect pins 2 and 3 to D+ and D- and turn that into USB.

You can conceivably do it using V-USB which does USB in software in conjunction with a few extra components.

You can also buy external serial to USB adapters which do the conversion externally. If you Google serial to usb adapter you will find quite a few for around $3.