Hi, thanks for reaching out. Here's an example of how to print username (BotBuilder Sample).
// the channel should sends the user name in the 'From' object
var userName = turnContext.Activity.From.Name;
await turnContext.SendActivityAsync("You are seeing this message because this was your first message ever to this bot.", cancellationToken: cancellationToken);
await turnContext.SendActivityAsync($"It is a good practice to welcome the user and provide personal greeting. For example, welcome {userName}.", cancellationToken: cancellationToken);