Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
The way of taking bath for a fasting person after having wet dream is similar to the way one who is not fasting does it except that the fasting person should not draw water deep into his nose since the Prophet (Sallallahu Alaihi wa Sallam) said: "Exaggerate when rinsing your nose unless you are fasting." [Reported by four Imams of Sunan].
As for details on this subject, please read the Fatwa: 81491.
Allah knows best.