Go to any driving centre to enrol in whatever class you want.
For you I think you need a class 2b although you know how to ride a
600cc. You have to start from scratch. Unless you got your licence
over there, you can apply Conversion Of A Foreign Driving Licence
To A Singapore Driving Licence.
Bring your Passport, NRIC, Valid qualified foreign driving licence,
Proof of date of passing driving test or date of first issue of
driving licence and Official translation if documents are not in
english.
If the information is not correct, please correct me. 
