First we create a string variable containing the .json file name and call the file stream.

string fileName = "weather.json";
using FileStream openStream = File.OpenRead(fileName);

Next call the deserialize method passing the stream as an argument.

WeatherForecast weatherForecast = 
await JsonSerializer.DeserializeAsync<WeatherForecast>(openStream);

Now finally print the resulting objects values.

Console.WriteLine($"Date: {weatherForecast.Date}");
Console.WriteLine($"TemperatureCelsius: {weatherForecast.TemperatureCelsius}");
Console.WriteLine($"Summary: {weatherForecast.Summary}");

As a bonus you can iterate over the resulting string array created during the deserialize actions.

foreach(string fc in weatherForecast.SummaryWords) {
    Console.WriteLine(fc);
}

Time to run the program and see your result!

Great work! You should feel proud of yourself!