How to post message in teams channel by using graph api?

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C#

Microsoft

API

graph

i have tried to post message in teams channel by using username and password with delegated permissions. but i am getting error. i am using certificate authentication for my tenant id and client id while setting up graph api client. but how to authenticate for username and password with delegated authentication?

What I have tried:

var graphClient = new GraphServiceClient(requestAdapter);

var requestBody = new ChatMessage
{
	Body = new ItemBody
	{
		Content = "Hello World",
	},
};
var result = await graphClient.Teams["{team-id}"].Channels["{channel-id}"].Messages.PostAsync(requestBody);