How to fill in html textbox from (c# )windows application

Question

I would like to do the following from a windows application:
 
1. Manually Opened a browser and navigate to a URL.
2. When i am at the correct URL in my browser window, i want to fill in data in the html textboxes on that page from my windows application.
3. When that is done i want to press a button.
 
Description:-
1.The URL (https://www.exple.com/login.html ) had already opened in anyone web browsers such as Mozilla Firefox or Google Chrome on local System.
It consists of Two Textboxes such as Username and Password .
2.I Want to fill in data in Username & Password Textbox on login html page
3.The Input (username & Password ) data is taken from C# Windows Application to URL(https://www.exple.com/login.html ) When Clicked Submit Button in C# Windows Application.
 
Note:
Google Chrome and Mozilla Firefox is currently used in my browser Window.
Internet Explorer(IE) never used in browser Window.
 
Please help me Friend
 
Thanks in Advance .
Zaid Ansari