Hi Fhasan,
Since you are new to CST, it is better to go through some CST tutorials first before jumping in to wilkinson design.
I found this excellent CST tutorial for beginners from a Hong Kong uni.**broken link removed**
For the wilkinson design problem, better to go through a little bit about single section wilkinsons from David Pozar's Microwave Engineering book or any other microwave text book.
For multisection designs Microwave101 **broken link removed** will be useful.
Since you are a postgrad student you may need some theories too. for that purpose refer to some papers such as:
[1] E. Wilkinson, “An N-Way Hybrid Power Divider,” Microwave Theory and Techniques, IRE Transactions on, vol. 8, no. 1, pp. 116-118, 1960.
[2] L. Parad and R. Moynihan, “Split-Tee Power Divider,” Microwave Theory and Techniques, IEEE Transactions on, vol. 13, no. 1, pp. 91-95, 1965.
[3] S. Cohn, “A Class of Broadband Three-Port TEM-Mode Hybrids,” Microwave Theory and Techniques, IEEE Transactions on, vol. 19, no. 2, pp. 110-116, 1968.
hope this will be useful.
regards,
per_lube