Integrate Dhan API Order Placement

My trading tool is built in .NET and I need a slim, working integration that lets me place a single-leg market order through the Dhan API. The job is intentionally narrow in scope: get one clean method into my existing codebase that accepts symbol, quantity, and side, then fires a market order and returns the API response.

Key points
• Language / stack: pure .NET (C#)
• Functionality: order placement only—no data retrieval or account management for now
• Order type: market order

Deliverables
1. A well-commented .NET class or method that calls the correct Dhan endpoint, signs the request with my API key/secret, and parses the success or error response.
2. A quick README or inline notes that show setup steps, required NuGet packages (if any), and how to swap in my live credentials.
3. A short test routine or Postman collection proving the call works on the Dhan sandbox (or live, if you have credentials).

Keep dependencies light, follow best practices for basic error handling, and structure the code so I can drop it straight into an existing Visual Studio project. I’m aiming for a concise, easily maintainable snippet rather than a full trading framework, so please focus only on what’s outlined above.