WCF service how to create

See more:

WCFServices

I have been assigned a task to craete a WCF service which able to insert or fetch record.I was provided with one dll,with the help of that I have to create.I am unable to see any method name not it's content.I downloaded one application which decompile assembly.Now I able to see content of it.There are 2 class,one class contain properties(which acsess through get and set method) another class contain method which add record and fetch record.How to create WCF service from that?I have already created lot of WCF service before that.In that case I have created cs file that in that created class who have properties(get,set) given name to class as datacontract and member as datamember.In service one class which implement interface.In interface just declare method and in interface define that method where I do inert/serach code and consumer application creating instance of service class and calling that method.But how to do in this situation?