Grand Master Ramos:
To become a Rogue, you need the appropriate level and token. Your level must be at least 20 to qualify to change profession. You also need a token to prove you have passed the Test of the Rogue, as well.
However, it seems that your level is not high enough, and you have not yet passed the Test of the Rogue, either. First, try to raise your level to 20 or higher. To take the Test of the Rogue, look for Captain Bezique. He is at the entrance to the harbor on the west side of the village. To become a Rogue, pass his test and bring back his Recommendation.