1. Create a new console application in a new, empty folder by running dotnet new console.
2. Add a reference for Alpaca .NET SDK with dotnet add package Alpaca.Markets.
3. Replace content of the auto-generated Programm.cs file with this code snippet:

using System;
using Alpaca.Markets;
using System.Threading.Tasks;

namespace AlpacaExample
{
    internal static class Program
    {
        private const String KEY_ID = "";

        private const String SECRET_KEY = "";

        public static async Task Main()
        {
            var client = Environments.Paper
                .GetAlpacaTradingClient(new SecretKey(KEY_ID, SECRET_KEY));

            var clock = await client.GetClockAsync();

            if (clock != null)
            {
                Console.WriteLine(
                    "Timestamp: {0}, NextOpen: {1}, NextClose: {2}",
                    clock.TimestampUtc, clock.NextOpenUtc, clock.NextCloseUtc);
            }
        }
    }
}

4. Replace KEY_ID and SECRET_KEY values with your own data from the Alpaca dashboard.
5. Run the sample application using dotnet run command and check the output. You should see information about the current market timestamp and the times that the market will open and close next.

See the UsageExamples project for near-to-real-world strategy implementation using this SDK and the Alpaca.Markets.Tests repository for SDK usage examples. The Wiki pages contain a lot of additional information about different aspects of this SDK (environments handling, authentication types, different order placement approaches, streaming client subscriptions handling, etc.).