Stupid question, but I cant get it

So, then I type my wallet adress on blockchain.info I immediately can see my balance, but from my project I can't type something like:

WalletAddress wa = new WalletAddress("17p49XUC2fw4Fn53WjZqYAm4APKqhNPEkY");
Console.WriteLine("My balance: " + wa.GetBalance() + "BTC");

and output would be like: My balance: 1.0023BTC

The easiest way to see my balance from bitcoin wallet?

No metter I use Blockchain Api or something else, but C#.

Sory for my bed england