Question: I went througha few Google Api docs for Windows Phone eg `https://developers.google.com/api-client-library/dotnet/apis/` but did not get the clear idea on how to implement the same. I want to find all the restaurants ina specified area. Any ideas on how it is supposed to be done on Windows Phone. And if not using Google Maps, does `Here Maps` help here ?

Answer: 
I suggest you to go with Here Maps API since I have implemented in one of my application. Its very easy to use Here Maps in your case. 

First go through [Windows Phone API - HereMaps](http://developer.nokia.com/resources/library/Lumia/change-history/archived-content/maps-and-navigation/guide-to-the-wp8-maps-api.html) which will help you to proceed with basic knowledge on Here Maps API.

As you said, first integrate your API's inside your application. With just a single term "**nearby restaurants**" passing it to a search term in Here Maps, It will get you all the nearby restaurants in your Here Maps along with the Route Navigation using Here Drive. 

Its very simple to use and easy to proceed. Hope it helps you.
You could go with the [Bing Maps REST Services](http://msdn.microsoft.com/en-us/library/ff701713.aspx) to search specifically what you want to. 

Have a look at this for more details : <http://alastaira.wordpress.com/2011/01/09/the-bing-maps-soap-search-service/>

Hope it helps!