Hi Pramod,
Following are the two scenario:
1 Is your .Net application running on same server where SharePoint is installed. If yes then you can use SharePoint server object model. Store the address of your web application is web.config and insert the data into SharePoint. Put a button on your page
and on click use the below code. Add the reference to Microsoft.Sharepoint.dll in your application.
SPSite myWebApp = new SPSite("your web application url");
SPWeb mySite = myWebApp.OpenWeb();
SPListItemCollection listItems = mySite.Lists[""Your List Name"].Items;
SPListItem item = listItems.Add();
item["Title"] = "Your Data";
item.Update();
}
2. If your application is installed on different server then you can user SharePoint Web Service to connect to Sharepoint and insert the data into sharepoint list.