To file a patent application in Singapore, you have to file Patents Form 1/8 together with the prescribed fee.
Your application should include a specification of your invention, i.e. the description, one or more claim(s) and drawing(s) (if any), and an abstract of your invention.
Default communications will be performed via electronic correspondences through IP2SG. Applicants are however still required to furnish to IPOS an address for service in Singapore. This is the address to which any correspondence from IPOS will be sent where necessary.
As the patent process is complex, you may wish to consider engaging the service of a registered patent agent .