how to search an enum variable for a specific member?

[bnathvbdotnet]

I have declared an enum as

enum PaymentFrequency : int

{
Monthly = 12,
Quarterly = 4,
SemiAnnual = 4,
Annual = 1

};

in the method I am writing, the parameter passed is any one of items in the enum (say Annual).

How to search an enum variable for 'Annual' and get the value which is 1 here.

thanks
nath