pc to arduino to rfid connection

hello... i'm new with arduino products.. and in just wanna ask how to interface this 3 device...schematic diageram will do.. thaks...in advance,...

Which RFID reader?

If the RFID is serial then use new software serial to connect it to the arduino so it dosen't interfere with the PC communications. If it is Weagand the use pins 2& 3 and enable the interrupts on those pins.