How to translate the signal coming from the tag to the reader ? RFID

I am trying to build an RFID reader and would like to know how to translate the signal coming from the tag to the reader into something useful. If anyone could help that would be great.

hi
this is raghu persuing M.E COMMUNICATIONS in BITS-PILANI
i read u r question ,solution is you can read the contents of the tag by using the concept of near field communication according to this tag may be active or passive when a reader kept nearer to it by the law magnetic field of induction (faraday law) the contents present in the tag will be induced in to the reader so that u can read the contents of tag