Hi Aabid,
First of all you decide which system you want to implement, then draw the schematic in paper and from that try to implement that in Optisystem using the components library that is available in optisystem. You can also go through the relevant topic design sample that is available at C:\Documents\OptiSystem 13 Samples\ and if you find any problem or error in you design, you can put that as a question in this forum.
Thanks