How To Impliment Security in WCF?

hi,

this is depending on which type of security mechnisum you required.
you can use certificate base security also
http://www.codeproject.com/Articles/18601/An-easy-way-to-use-certificates-for-WCF-security

you must have to select proper binding for same
http://msdn.microsoft.com/en-IN/library/ms731884.aspx
http://wcfsecurity.codeplex.com/

hope this will help you.