To find your Rolex's serial number remove the strap at the 6 o'clock position and the serial number will be engraved on the case between the lugs.
It is 5-7 digits and may start with a letter. It will NOT have letters in the middle. The Rolex model reference can be found between the lugs on the opposite side of the watch, that is 4-6 digits long and is numbers only. The Rolex model reference will decode to tell you the model, the material and the bezel style. You can also look up the date from the Rolex movement/caliber number etched directly on the Rolex movement using my Rolex movement database or date the strap/clasp using my Rolex clasp date decoder.
Please note, Rolex watches made after 2010 no longer have sequential serial numbers and cannot be dated this way.