Wcf azure Authorization

Hi i have a query regarding to azure wfc authorization i have the authentic user access token now i want to authorize the user through wcf by its access token how can i do this .......?

AuthenticationResult result =null;try{
            result = authContext.AcquireToken(todoListResourceId, clientId, redirectUri,PromptBehavior.Always);

I have my access token in "result"