Hi Muhammad, i believe the examples library will be of help to you for your project. You can find an example of WDM PON system in the samples library. This example should give you an idea of what to do. In the Optisystem software click file, and click example. The file WDM PON example can be found by following the file path below.
Note: your optisystem samples folder may be saved somewhere else.
C:\Users\NAME\Documents\OptiSystem 16.0 Samples\Metro and access systems\PON and CDMA systems